<!DOCTYPE html> <html> <head> <title>underscore.js</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <meta name="viewport" content="width=device-width, target-densitydpi=160dpi, initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"> <link rel="stylesheet" media="all" href="docco.css" /> </head> <body> <div id="container"> <div id="background"></div> <ul class="sections"> <li id="title"> <div class="annotation"> <h1>underscore.js</h1> </div> </li> <li id="section-1"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-1">¶</a> </div> <pre><code>Underscore.js 1.5.0 http://underscorejs.org (c) 2009-2011 Jeremy Ashkenas, DocumentCloud Inc. (c) 2011-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors Underscore may be freely distributed under the MIT license.</code></pre> </div> <div class="content"><div class='highlight'><pre> (<span class="keyword">function</span>() {</pre></div></div> </li> <li id="section-2"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-2">¶</a> </div> <h2>Baseline setup</h2> </div> </li> <li id="section-3"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-3">¶</a> </div> </div> </li> <li id="section-4"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-4">¶</a> </div> <p>Establish the root object, <code>window</code> in the browser, or <code>global</code> on the server. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> root = <span class="keyword">this</span>;</pre></div></div> </li> <li id="section-5"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-5">¶</a> </div> <p>Save the previous value of the <code>_</code> variable. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> previousUnderscore = root._;</pre></div></div> </li> <li id="section-6"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-6">¶</a> </div> <p>Establish the object that gets returned to break out of a loop iteration. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> breaker = {};</pre></div></div> </li> <li id="section-7"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-7">¶</a> </div> <p>Save bytes in the minified (but not gzipped) version: </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;</pre></div></div> </li> <li id="section-8"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-8">¶</a> </div> <p>Create quick reference variables for speed access to core prototypes. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> push = ArrayProto.push, slice = ArrayProto.slice, concat = ArrayProto.concat, toString = ObjProto.toString, hasOwnProperty = ObjProto.hasOwnProperty;</pre></div></div> </li> <li id="section-9"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-9">¶</a> </div> <p>All <strong>ECMAScript 5</strong> native function implementations that we hope to use are declared here. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> nativeForEach = ArrayProto.forEach, nativeMap = ArrayProto.map, nativeReduce = ArrayProto.reduce, nativeReduceRight = ArrayProto.reduceRight, nativeFilter = ArrayProto.filter, nativeEvery = ArrayProto.every, nativeSome = ArrayProto.some, nativeIndexOf = ArrayProto.indexOf, nativeLastIndexOf = ArrayProto.lastIndexOf, nativeIsArray = Array.isArray, nativeKeys = Object.keys, nativeBind = FuncProto.bind;</pre></div></div> </li> <li id="section-10"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-10">¶</a> </div> <p>Create a safe reference to the Underscore object for use below. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> _ = <span class="keyword">function</span>(obj) { <span class="keyword">if</span> (obj <span class="keyword">instanceof</span> _) <span class="keyword">return</span> obj; <span class="keyword">if</span> (!(<span class="keyword">this</span> <span class="keyword">instanceof</span> _)) <span class="keyword">return</span> <span class="keyword">new</span> _(obj); <span class="keyword">this</span>._wrapped = obj; };</pre></div></div> </li> <li id="section-11"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-11">¶</a> </div> <p>Export the Underscore object for <strong>Node.js</strong>, with backwards-compatibility for the old <code>require()</code> API. If we're in the browser, add <code>_</code> as a global object via a string identifier, for Closure Compiler "advanced" mode. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (<span class="keyword">typeof</span> exports !== <span class="string">'undefined'</span>) { <span class="keyword">if</span> (<span class="keyword">typeof</span> module !== <span class="string">'undefined'</span> && module.exports) { exports = module.exports = _; } exports._ = _; } <span class="keyword">else</span> { root._ = _; }</pre></div></div> </li> <li id="section-12"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-12">¶</a> </div> <p>Current version. </p> </div> <div class="content"><div class='highlight'><pre> _.VERSION = <span class="string">'1.5.0'</span>;</pre></div></div> </li> <li id="section-13"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-13">¶</a> </div> <h2>Collection Functions</h2> </div> </li> <li id="section-14"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-14">¶</a> </div> </div> </li> <li id="section-15"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-15">¶</a> </div> <p>The cornerstone, an <code>each</code> implementation, aka <code>forEach</code>. Handles objects with the built-in <code>forEach</code>, arrays, and raw objects. Delegates to <strong>ECMAScript 5</strong>'s native <code>forEach</code> if available. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> each = _.each = _.forEach = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span>; <span class="keyword">if</span> (nativeForEach && obj.forEach === nativeForEach) { obj.forEach(iterator, context); } <span class="keyword">else</span> <span class="keyword">if</span> (obj.length === +obj.length) { <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>, l = obj.length; i < l; i++) { <span class="keyword">if</span> (iterator.call(context, obj[i], i, obj) === breaker) <span class="keyword">return</span>; } } <span class="keyword">else</span> { <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) { <span class="keyword">if</span> (_.has(obj, key)) { <span class="keyword">if</span> (iterator.call(context, obj[key], key, obj) === breaker) <span class="keyword">return</span>; } } } };</pre></div></div> </li> <li id="section-16"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-16">¶</a> </div> <p>Return the results of applying the iterator to each element. Delegates to <strong>ECMAScript 5</strong>'s native <code>map</code> if available. </p> </div> <div class="content"><div class='highlight'><pre> _.map = _.collect = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">var</span> results = []; <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> results; <span class="keyword">if</span> (nativeMap && obj.map === nativeMap) <span class="keyword">return</span> obj.map(iterator, context); each(obj, <span class="keyword">function</span>(value, index, list) { results.push(iterator.call(context, value, index, list)); }); <span class="keyword">return</span> results; }; <span class="keyword">var</span> reduceError = <span class="string">'Reduce of empty array with no initial value'</span>;</pre></div></div> </li> <li id="section-17"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-17">¶</a> </div> <p><strong>Reduce</strong> builds up a single result from a list of values, aka <code>inject</code>, or <code>foldl</code>. Delegates to <strong>ECMAScript 5</strong>'s native <code>reduce</code> if available. </p> </div> <div class="content"><div class='highlight'><pre> _.reduce = _.foldl = _.inject = <span class="keyword">function</span>(obj, iterator, memo, context) { <span class="keyword">var</span> initial = arguments.length > <span class="number">2</span>; <span class="keyword">if</span> (obj == <span class="literal">null</span>) obj = []; <span class="keyword">if</span> (nativeReduce && obj.reduce === nativeReduce) { <span class="keyword">if</span> (context) iterator = _.bind(iterator, context); <span class="keyword">return</span> initial ? obj.reduce(iterator, memo) : obj.reduce(iterator); } each(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">if</span> (!initial) { memo = value; initial = <span class="literal">true</span>; } <span class="keyword">else</span> { memo = iterator.call(context, memo, value, index, list); } }); <span class="keyword">if</span> (!initial) <span class="keyword">throw</span> <span class="keyword">new</span> TypeError(reduceError); <span class="keyword">return</span> memo; };</pre></div></div> </li> <li id="section-18"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-18">¶</a> </div> <p>The right-associative version of reduce, also known as <code>foldr</code>. Delegates to <strong>ECMAScript 5</strong>'s native <code>reduceRight</code> if available. </p> </div> <div class="content"><div class='highlight'><pre> _.reduceRight = _.foldr = <span class="keyword">function</span>(obj, iterator, memo, context) { <span class="keyword">var</span> initial = arguments.length > <span class="number">2</span>; <span class="keyword">if</span> (obj == <span class="literal">null</span>) obj = []; <span class="keyword">if</span> (nativeReduceRight && obj.reduceRight === nativeReduceRight) { <span class="keyword">if</span> (context) iterator = _.bind(iterator, context); <span class="keyword">return</span> initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator); } <span class="keyword">var</span> length = obj.length; <span class="keyword">if</span> (length !== +length) { <span class="keyword">var</span> keys = _.keys(obj); length = keys.length; } each(obj, <span class="keyword">function</span>(value, index, list) { index = keys ? keys[--length] : --length; <span class="keyword">if</span> (!initial) { memo = obj[index]; initial = <span class="literal">true</span>; } <span class="keyword">else</span> { memo = iterator.call(context, memo, obj[index], index, list); } }); <span class="keyword">if</span> (!initial) <span class="keyword">throw</span> <span class="keyword">new</span> TypeError(reduceError); <span class="keyword">return</span> memo; };</pre></div></div> </li> <li id="section-19"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-19">¶</a> </div> <p>Return the first value which passes a truth test. Aliased as <code>detect</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.find = _.detect = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">var</span> result; any(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">if</span> (iterator.call(context, value, index, list)) { result = value; <span class="keyword">return</span> <span class="literal">true</span>; } }); <span class="keyword">return</span> result; };</pre></div></div> </li> <li id="section-20"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-20">¶</a> </div> <p>Return all the elements that pass a truth test. Delegates to <strong>ECMAScript 5</strong>'s native <code>filter</code> if available. Aliased as <code>select</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.filter = _.select = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">var</span> results = []; <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> results; <span class="keyword">if</span> (nativeFilter && obj.filter === nativeFilter) <span class="keyword">return</span> obj.filter(iterator, context); each(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">if</span> (iterator.call(context, value, index, list)) results.push(value); }); <span class="keyword">return</span> results; };</pre></div></div> </li> <li id="section-21"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-21">¶</a> </div> <p>Return all the elements for which a truth test fails. </p> </div> <div class="content"><div class='highlight'><pre> _.reject = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">return</span> _.filter(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">return</span> !iterator.call(context, value, index, list); }, context); };</pre></div></div> </li> <li id="section-22"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-22">¶</a> </div> <p>Determine whether all of the elements match a truth test. Delegates to <strong>ECMAScript 5</strong>'s native <code>every</code> if available. Aliased as <code>all</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.every = _.all = <span class="keyword">function</span>(obj, iterator, context) { iterator || (iterator = _.identity); <span class="keyword">var</span> result = <span class="literal">true</span>; <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> result; <span class="keyword">if</span> (nativeEvery && obj.every === nativeEvery) <span class="keyword">return</span> obj.every(iterator, context); each(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">if</span> (!(result = result && iterator.call(context, value, index, list))) <span class="keyword">return</span> breaker; }); <span class="keyword">return</span> !!result; };</pre></div></div> </li> <li id="section-23"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-23">¶</a> </div> <p>Determine if at least one element in the object matches a truth test. Delegates to <strong>ECMAScript 5</strong>'s native <code>some</code> if available. Aliased as <code>any</code>. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> any = _.some = _.any = <span class="keyword">function</span>(obj, iterator, context) { iterator || (iterator = _.identity); <span class="keyword">var</span> result = <span class="literal">false</span>; <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> result; <span class="keyword">if</span> (nativeSome && obj.some === nativeSome) <span class="keyword">return</span> obj.some(iterator, context); each(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">if</span> (result || (result = iterator.call(context, value, index, list))) <span class="keyword">return</span> breaker; }); <span class="keyword">return</span> !!result; };</pre></div></div> </li> <li id="section-24"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-24">¶</a> </div> <p>Determine if the array or object contains a given value (using <code>===</code>). Aliased as <code>include</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.contains = _.include = <span class="keyword">function</span>(obj, target) { <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> <span class="literal">false</span>; <span class="keyword">if</span> (nativeIndexOf && obj.indexOf === nativeIndexOf) <span class="keyword">return</span> obj.indexOf(target) != -<span class="number">1</span>; <span class="keyword">return</span> any(obj, <span class="keyword">function</span>(value) { <span class="keyword">return</span> value === target; }); };</pre></div></div> </li> <li id="section-25"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-25">¶</a> </div> <p>Invoke a method (with arguments) on every item in a collection. </p> </div> <div class="content"><div class='highlight'><pre> _.invoke = <span class="keyword">function</span>(obj, method) { <span class="keyword">var</span> args = slice.call(arguments, <span class="number">2</span>); <span class="keyword">var</span> isFunc = _.isFunction(method); <span class="keyword">return</span> _.map(obj, <span class="keyword">function</span>(value) { <span class="keyword">return</span> (isFunc ? method : value[method]).apply(value, args); }); };</pre></div></div> </li> <li id="section-26"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-26">¶</a> </div> <p>Convenience version of a common use case of <code>map</code>: fetching a property. </p> </div> <div class="content"><div class='highlight'><pre> _.pluck = <span class="keyword">function</span>(obj, key) { <span class="keyword">return</span> _.map(obj, <span class="keyword">function</span>(value){ <span class="keyword">return</span> value[key]; }); };</pre></div></div> </li> <li id="section-27"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-27">¶</a> </div> <p>Convenience version of a common use case of <code>filter</code>: selecting only objects containing specific <code>key:value</code> pairs. </p> </div> <div class="content"><div class='highlight'><pre> _.where = <span class="keyword">function</span>(obj, attrs, first) { <span class="keyword">if</span> (_.isEmpty(attrs)) <span class="keyword">return</span> first ? <span class="keyword">void</span> <span class="number">0</span> : []; <span class="keyword">return</span> _[first ? <span class="string">'find'</span> : <span class="string">'filter'</span>](obj, <span class="keyword">function</span>(value) { <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> attrs) { <span class="keyword">if</span> (attrs[key] !== value[key]) <span class="keyword">return</span> <span class="literal">false</span>; } <span class="keyword">return</span> <span class="literal">true</span>; }); };</pre></div></div> </li> <li id="section-28"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-28">¶</a> </div> <p>Convenience version of a common use case of <code>find</code>: getting the first object containing specific <code>key:value</code> pairs. </p> </div> <div class="content"><div class='highlight'><pre> _.findWhere = <span class="keyword">function</span>(obj, attrs) { <span class="keyword">return</span> _.where(obj, attrs, <span class="literal">true</span>); };</pre></div></div> </li> <li id="section-29"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-29">¶</a> </div> <p>Return the maximum element or (element-based computation). Can't optimize arrays of integers longer than 65,535 elements. See <a href="https://bugs.webkit.org/show_bug.cgi?id=80797">WebKit Bug 80797</a> </p> </div> <div class="content"><div class='highlight'><pre> _.max = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">if</span> (!iterator && _.isArray(obj) && obj[<span class="number">0</span>] === +obj[<span class="number">0</span>] && obj.length < <span class="number">65535</span>) { <span class="keyword">return</span> Math.max.apply(Math, obj); } <span class="keyword">if</span> (!iterator && _.isEmpty(obj)) <span class="keyword">return</span> -<span class="literal">Infinity</span>; <span class="keyword">var</span> result = {computed : -<span class="literal">Infinity</span>, value: -<span class="literal">Infinity</span>}; each(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">var</span> computed = iterator ? iterator.call(context, value, index, list) : value; computed > result.computed && (result = {value : value, computed : computed}); }); <span class="keyword">return</span> result.value; };</pre></div></div> </li> <li id="section-30"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-30">¶</a> </div> <p>Return the minimum element (or element-based computation). </p> </div> <div class="content"><div class='highlight'><pre> _.min = <span class="keyword">function</span>(obj, iterator, context) { <span class="keyword">if</span> (!iterator && _.isArray(obj) && obj[<span class="number">0</span>] === +obj[<span class="number">0</span>] && obj.length < <span class="number">65535</span>) { <span class="keyword">return</span> Math.min.apply(Math, obj); } <span class="keyword">if</span> (!iterator && _.isEmpty(obj)) <span class="keyword">return</span> <span class="literal">Infinity</span>; <span class="keyword">var</span> result = {computed : <span class="literal">Infinity</span>, value: <span class="literal">Infinity</span>}; each(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">var</span> computed = iterator ? iterator.call(context, value, index, list) : value; computed < result.computed && (result = {value : value, computed : computed}); }); <span class="keyword">return</span> result.value; };</pre></div></div> </li> <li id="section-31"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-31">¶</a> </div> <p>Shuffle an array. </p> </div> <div class="content"><div class='highlight'><pre> _.shuffle = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> rand; <span class="keyword">var</span> index = <span class="number">0</span>; <span class="keyword">var</span> shuffled = []; each(obj, <span class="keyword">function</span>(value) { rand = _.random(index++); shuffled[index - <span class="number">1</span>] = shuffled[rand]; shuffled[rand] = value; }); <span class="keyword">return</span> shuffled; };</pre></div></div> </li> <li id="section-32"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-32">¶</a> </div> <p>An internal function to generate lookup iterators. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> lookupIterator = <span class="keyword">function</span>(value) { <span class="keyword">return</span> _.isFunction(value) ? value : <span class="keyword">function</span>(obj){ <span class="keyword">return</span> obj[value]; }; };</pre></div></div> </li> <li id="section-33"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-33">¶</a> </div> <p>Sort the object's values by a criterion produced by an iterator. </p> </div> <div class="content"><div class='highlight'><pre> _.sortBy = <span class="keyword">function</span>(obj, value, context) { <span class="keyword">var</span> iterator = lookupIterator(value); <span class="keyword">return</span> _.pluck(_.map(obj, <span class="keyword">function</span>(value, index, list) { <span class="keyword">return</span> { value : value, index : index, criteria : iterator.call(context, value, index, list) }; }).sort(<span class="keyword">function</span>(left, right) { <span class="keyword">var</span> a = left.criteria; <span class="keyword">var</span> b = right.criteria; <span class="keyword">if</span> (a !== b) { <span class="keyword">if</span> (a > b || a === <span class="keyword">void</span> <span class="number">0</span>) <span class="keyword">return</span> <span class="number">1</span>; <span class="keyword">if</span> (a < b || b === <span class="keyword">void</span> <span class="number">0</span>) <span class="keyword">return</span> -<span class="number">1</span>; } <span class="keyword">return</span> left.index < right.index ? -<span class="number">1</span> : <span class="number">1</span>; }), <span class="string">'value'</span>); };</pre></div></div> </li> <li id="section-34"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-34">¶</a> </div> <p>An internal function used for aggregate "group by" operations. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> group = <span class="keyword">function</span>(obj, value, context, behavior) { <span class="keyword">var</span> result = {}; <span class="keyword">var</span> iterator = lookupIterator(value == <span class="literal">null</span> ? _.identity : value); each(obj, <span class="keyword">function</span>(value, index) { <span class="keyword">var</span> key = iterator.call(context, value, index, obj); behavior(result, key, value); }); <span class="keyword">return</span> result; };</pre></div></div> </li> <li id="section-35"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-35">¶</a> </div> <p>Groups the object's values by a criterion. Pass either a string attribute to group by, or a function that returns the criterion. </p> </div> <div class="content"><div class='highlight'><pre> _.groupBy = <span class="keyword">function</span>(obj, value, context) { <span class="keyword">return</span> group(obj, value, context, <span class="keyword">function</span>(result, key, value) { (_.has(result, key) ? result[key] : (result[key] = [])).push(value); }); };</pre></div></div> </li> <li id="section-36"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-36">¶</a> </div> <p>Counts instances of an object that group by a certain criterion. Pass either a string attribute to count by, or a function that returns the criterion. </p> </div> <div class="content"><div class='highlight'><pre> _.countBy = <span class="keyword">function</span>(obj, value, context) { <span class="keyword">return</span> group(obj, value, context, <span class="keyword">function</span>(result, key) { <span class="keyword">if</span> (!_.has(result, key)) result[key] = <span class="number">0</span>; result[key]++; }); };</pre></div></div> </li> <li id="section-37"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-37">¶</a> </div> <p>Use a comparator function to figure out the smallest index at which an object should be inserted so as to maintain order. Uses binary search. </p> </div> <div class="content"><div class='highlight'><pre> _.sortedIndex = <span class="keyword">function</span>(array, obj, iterator, context) { iterator = iterator == <span class="literal">null</span> ? _.identity : lookupIterator(iterator); <span class="keyword">var</span> value = iterator.call(context, obj); <span class="keyword">var</span> low = <span class="number">0</span>, high = array.length; <span class="keyword">while</span> (low < high) { <span class="keyword">var</span> mid = (low + high) >>> <span class="number">1</span>; iterator.call(context, array[mid]) < value ? low = mid + <span class="number">1</span> : high = mid; } <span class="keyword">return</span> low; };</pre></div></div> </li> <li id="section-38"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-38">¶</a> </div> <p>Safely create a real, live array from anything iterable. </p> </div> <div class="content"><div class='highlight'><pre> _.toArray = <span class="keyword">function</span>(obj) { <span class="keyword">if</span> (!obj) <span class="keyword">return</span> []; <span class="keyword">if</span> (_.isArray(obj)) <span class="keyword">return</span> slice.call(obj); <span class="keyword">if</span> (obj.length === +obj.length) <span class="keyword">return</span> _.map(obj, _.identity); <span class="keyword">return</span> _.values(obj); };</pre></div></div> </li> <li id="section-39"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-39">¶</a> </div> <p>Return the number of elements in an object. </p> </div> <div class="content"><div class='highlight'><pre> _.size = <span class="keyword">function</span>(obj) { <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> <span class="number">0</span>; <span class="keyword">return</span> (obj.length === +obj.length) ? obj.length : _.keys(obj).length; };</pre></div></div> </li> <li id="section-40"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-40">¶</a> </div> <h2>Array Functions</h2> </div> </li> <li id="section-41"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-41">¶</a> </div> </div> </li> <li id="section-42"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-42">¶</a> </div> <p>Get the first element of an array. Passing <strong>n</strong> will return the first N values in the array. Aliased as <code>head</code> and <code>take</code>. The <strong>guard</strong> check allows it to work with <code>_.map</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.first = _.head = _.take = <span class="keyword">function</span>(array, n, guard) { <span class="keyword">if</span> (array == <span class="literal">null</span>) <span class="keyword">return</span> <span class="keyword">void</span> <span class="number">0</span>; <span class="keyword">return</span> (n != <span class="literal">null</span>) && !guard ? slice.call(array, <span class="number">0</span>, n) : array[<span class="number">0</span>]; };</pre></div></div> </li> <li id="section-43"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-43">¶</a> </div> <p>Returns everything but the last entry of the array. Especially useful on the arguments object. Passing <strong>n</strong> will return all the values in the array, excluding the last N. The <strong>guard</strong> check allows it to work with <code>_.map</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.initial = <span class="keyword">function</span>(array, n, guard) { <span class="keyword">return</span> slice.call(array, <span class="number">0</span>, array.length - ((n == <span class="literal">null</span>) || guard ? <span class="number">1</span> : n)); };</pre></div></div> </li> <li id="section-44"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-44">¶</a> </div> <p>Get the last element of an array. Passing <strong>n</strong> will return the last N values in the array. The <strong>guard</strong> check allows it to work with <code>_.map</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.last = <span class="keyword">function</span>(array, n, guard) { <span class="keyword">if</span> (array == <span class="literal">null</span>) <span class="keyword">return</span> <span class="keyword">void</span> <span class="number">0</span>; <span class="keyword">if</span> ((n != <span class="literal">null</span>) && !guard) { <span class="keyword">return</span> slice.call(array, Math.max(array.length - n, <span class="number">0</span>)); } <span class="keyword">else</span> { <span class="keyword">return</span> array[array.length - <span class="number">1</span>]; } };</pre></div></div> </li> <li id="section-45"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-45">¶</a> </div> <p>Returns everything but the first entry of the array. Aliased as <code>tail</code> and <code>drop</code>. Especially useful on the arguments object. Passing an <strong>n</strong> will return the rest N values in the array. The <strong>guard</strong> check allows it to work with <code>_.map</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.rest = _.tail = _.drop = <span class="keyword">function</span>(array, n, guard) { <span class="keyword">return</span> slice.call(array, (n == <span class="literal">null</span>) || guard ? <span class="number">1</span> : n); };</pre></div></div> </li> <li id="section-46"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-46">¶</a> </div> <p>Trim out all falsy values from an array. </p> </div> <div class="content"><div class='highlight'><pre> _.compact = <span class="keyword">function</span>(array) { <span class="keyword">return</span> _.filter(array, _.identity); };</pre></div></div> </li> <li id="section-47"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-47">¶</a> </div> <p>Internal implementation of a recursive <code>flatten</code> function. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> flatten = <span class="keyword">function</span>(input, shallow, output) { <span class="keyword">if</span> (shallow && _.every(input, _.isArray)) { <span class="keyword">return</span> concat.apply(output, input); } each(input, <span class="keyword">function</span>(value) { <span class="keyword">if</span> (_.isArray(value) || _.isArguments(value)) { shallow ? push.apply(output, value) : flatten(value, shallow, output); } <span class="keyword">else</span> { output.push(value); } }); <span class="keyword">return</span> output; };</pre></div></div> </li> <li id="section-48"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-48">¶</a> </div> <p>Return a completely flattened version of an array. </p> </div> <div class="content"><div class='highlight'><pre> _.flatten = <span class="keyword">function</span>(array, shallow) { <span class="keyword">return</span> flatten(array, shallow, []); };</pre></div></div> </li> <li id="section-49"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-49">¶</a> </div> <p>Return a version of the array that does not contain the specified value(s). </p> </div> <div class="content"><div class='highlight'><pre> _.without = <span class="keyword">function</span>(array) { <span class="keyword">return</span> _.difference(array, slice.call(arguments, <span class="number">1</span>)); };</pre></div></div> </li> <li id="section-50"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-50">¶</a> </div> <p>Produce a duplicate-free version of the array. If the array has already been sorted, you have the option of using a faster algorithm. Aliased as <code>unique</code>. </p> </div> <div class="content"><div class='highlight'><pre> _.uniq = _.unique = <span class="keyword">function</span>(array, isSorted, iterator, context) { <span class="keyword">if</span> (_.isFunction(isSorted)) { context = iterator; iterator = isSorted; isSorted = <span class="literal">false</span>; } <span class="keyword">var</span> initial = iterator ? _.map(array, iterator, context) : array; <span class="keyword">var</span> results = []; <span class="keyword">var</span> seen = []; each(initial, <span class="keyword">function</span>(value, index) { <span class="keyword">if</span> (isSorted ? (!index || seen[seen.length - <span class="number">1</span>] !== value) : !_.contains(seen, value)) { seen.push(value); results.push(array[index]); } }); <span class="keyword">return</span> results; };</pre></div></div> </li> <li id="section-51"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-51">¶</a> </div> <p>Produce an array that contains the union: each distinct element from all of the passed-in arrays. </p> </div> <div class="content"><div class='highlight'><pre> _.union = <span class="keyword">function</span>() { <span class="keyword">return</span> _.uniq(_.flatten(arguments, <span class="literal">true</span>)); };</pre></div></div> </li> <li id="section-52"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-52">¶</a> </div> <p>Produce an array that contains every item shared between all the passed-in arrays. </p> </div> <div class="content"><div class='highlight'><pre> _.intersection = <span class="keyword">function</span>(array) { <span class="keyword">var</span> rest = slice.call(arguments, <span class="number">1</span>); <span class="keyword">return</span> _.filter(_.uniq(array), <span class="keyword">function</span>(item) { <span class="keyword">return</span> _.every(rest, <span class="keyword">function</span>(other) { <span class="keyword">return</span> _.indexOf(other, item) >= <span class="number">0</span>; }); }); };</pre></div></div> </li> <li id="section-53"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-53">¶</a> </div> <p>Take the difference between one array and a number of other arrays. Only the elements present in just the first array will remain. </p> </div> <div class="content"><div class='highlight'><pre> _.difference = <span class="keyword">function</span>(array) { <span class="keyword">var</span> rest = concat.apply(ArrayProto, slice.call(arguments, <span class="number">1</span>)); <span class="keyword">return</span> _.filter(array, <span class="keyword">function</span>(value){ <span class="keyword">return</span> !_.contains(rest, value); }); };</pre></div></div> </li> <li id="section-54"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-54">¶</a> </div> <p>Zip together multiple lists into a single array -- elements that share an index go together. </p> </div> <div class="content"><div class='highlight'><pre> _.zip = <span class="keyword">function</span>() { <span class="keyword">return</span> _.unzip.apply(_, slice.call(arguments)); };</pre></div></div> </li> <li id="section-55"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-55">¶</a> </div> <p>The inverse operation to <code>_.zip</code>. If given an array of pairs it returns an array of the paired elements split into two left and right element arrays, if given an array of triples it returns a three element array and so on. For example, <code>_.unzip</code> given <code>[['a',1],['b',2],['c',3]]</code> returns the array [['a','b','c'],[1,2,3]]. </p> </div> <div class="content"><div class='highlight'><pre> _.unzip = <span class="keyword">function</span>() { <span class="keyword">var</span> length = _.max(_.pluck(arguments, <span class="string">"length"</span>).concat(<span class="number">0</span>)); <span class="keyword">var</span> results = <span class="keyword">new</span> Array(length); <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>; i < length; i++) { results[i] = _.pluck(arguments, <span class="string">''</span> + i); } <span class="keyword">return</span> results; };</pre></div></div> </li> <li id="section-56"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-56">¶</a> </div> <p>Converts lists into objects. Pass either a single array of <code>[key, value]</code> pairs, or two parallel arrays of the same length -- one of keys, and one of the corresponding values. </p> </div> <div class="content"><div class='highlight'><pre> _.object = <span class="keyword">function</span>(list, values) { <span class="keyword">if</span> (list == <span class="literal">null</span>) <span class="keyword">return</span> {}; <span class="keyword">var</span> result = {}; <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>, l = list.length; i < l; i++) { <span class="keyword">if</span> (values) { result[list[i]] = values[i]; } <span class="keyword">else</span> { result[list[i][<span class="number">0</span>]] = list[i][<span class="number">1</span>]; } } <span class="keyword">return</span> result; };</pre></div></div> </li> <li id="section-57"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-57">¶</a> </div> <p>If the browser doesn't supply us with indexOf (I'm looking at you, <strong>MSIE</strong>), we need this function. Return the position of the first occurrence of an item in an array, or -1 if the item is not included in the array. Delegates to <strong>ECMAScript 5</strong>'s native <code>indexOf</code> if available. If the array is large and already in sort order, pass <code>true</code> for <strong>isSorted</strong> to use binary search. </p> </div> <div class="content"><div class='highlight'><pre> _.indexOf = <span class="keyword">function</span>(array, item, isSorted) { <span class="keyword">if</span> (array == <span class="literal">null</span>) <span class="keyword">return</span> -<span class="number">1</span>; <span class="keyword">var</span> i = <span class="number">0</span>, l = array.length; <span class="keyword">if</span> (isSorted) { <span class="keyword">if</span> (<span class="keyword">typeof</span> isSorted == <span class="string">'number'</span>) { i = (isSorted < <span class="number">0</span> ? Math.max(<span class="number">0</span>, l + isSorted) : isSorted); } <span class="keyword">else</span> { i = _.sortedIndex(array, item); <span class="keyword">return</span> array[i] === item ? i : -<span class="number">1</span>; } } <span class="keyword">if</span> (nativeIndexOf && array.indexOf === nativeIndexOf) <span class="keyword">return</span> array.indexOf(item, isSorted); <span class="keyword">for</span> (; i < l; i++) <span class="keyword">if</span> (array[i] === item) <span class="keyword">return</span> i; <span class="keyword">return</span> -<span class="number">1</span>; };</pre></div></div> </li> <li id="section-58"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-58">¶</a> </div> <p>Delegates to <strong>ECMAScript 5</strong>'s native <code>lastIndexOf</code> if available. </p> </div> <div class="content"><div class='highlight'><pre> _.lastIndexOf = <span class="keyword">function</span>(array, item, from) { <span class="keyword">if</span> (array == <span class="literal">null</span>) <span class="keyword">return</span> -<span class="number">1</span>; <span class="keyword">var</span> hasIndex = from != <span class="literal">null</span>; <span class="keyword">if</span> (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) { <span class="keyword">return</span> hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item); } <span class="keyword">var</span> i = (hasIndex ? from : array.length); <span class="keyword">while</span> (i--) <span class="keyword">if</span> (array[i] === item) <span class="keyword">return</span> i; <span class="keyword">return</span> -<span class="number">1</span>; };</pre></div></div> </li> <li id="section-59"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-59">¶</a> </div> <p>Generate an integer Array containing an arithmetic progression. A port of the native Python <code>range()</code> function. See <a href="http://docs.python.org/library/functions.html#range">the Python documentation</a>. </p> </div> <div class="content"><div class='highlight'><pre> _.range = <span class="keyword">function</span>(start, stop, step) { <span class="keyword">if</span> (arguments.length <= <span class="number">1</span>) { stop = start || <span class="number">0</span>; start = <span class="number">0</span>; } step = arguments[<span class="number">2</span>] || <span class="number">1</span>; <span class="keyword">var</span> len = Math.max(Math.ceil((stop - start) / step), <span class="number">0</span>); <span class="keyword">var</span> idx = <span class="number">0</span>; <span class="keyword">var</span> range = <span class="keyword">new</span> Array(len); <span class="keyword">while</span>(idx < len) { range[idx++] = start; start += step; } <span class="keyword">return</span> range; };</pre></div></div> </li> <li id="section-60"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-60">¶</a> </div> <h2>Function (ahem) Functions</h2> </div> </li> <li id="section-61"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-61">¶</a> </div> </div> </li> <li id="section-62"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-62">¶</a> </div> <p>Reusable constructor function for prototype setting. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> ctor = <span class="keyword">function</span>(){};</pre></div></div> </li> <li id="section-63"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-63">¶</a> </div> <p>Create a function bound to a given object (assigning <code>this</code>, and arguments, optionally). Delegates to <strong>ECMAScript 5</strong>'s native <code>Function.bind</code> if available. </p> </div> <div class="content"><div class='highlight'><pre> _.bind = <span class="keyword">function</span>(func, context) { <span class="keyword">var</span> args, bound; <span class="keyword">if</span> (nativeBind && func.bind === nativeBind) <span class="keyword">return</span> nativeBind.apply(func, slice.call(arguments, <span class="number">1</span>)); <span class="keyword">if</span> (!_.isFunction(func)) <span class="keyword">throw</span> <span class="keyword">new</span> TypeError; args = slice.call(arguments, <span class="number">2</span>); <span class="keyword">return</span> bound = <span class="keyword">function</span>() { <span class="keyword">if</span> (!(<span class="keyword">this</span> <span class="keyword">instanceof</span> bound)) <span class="keyword">return</span> func.apply(context, args.concat(slice.call(arguments))); ctor.prototype = func.prototype; <span class="keyword">var</span> self = <span class="keyword">new</span> ctor; ctor.prototype = <span class="literal">null</span>; <span class="keyword">var</span> result = func.apply(self, args.concat(slice.call(arguments))); <span class="keyword">if</span> (Object(result) === result) <span class="keyword">return</span> result; <span class="keyword">return</span> self; }; };</pre></div></div> </li> <li id="section-64"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-64">¶</a> </div> <p>Partially apply a function by creating a version that has had some of its arguments pre-filled, without changing its dynamic <code>this</code> context. </p> </div> <div class="content"><div class='highlight'><pre> _.partial = <span class="keyword">function</span>(func) { <span class="keyword">var</span> args = slice.call(arguments, <span class="number">1</span>); <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">return</span> func.apply(<span class="keyword">this</span>, args.concat(slice.call(arguments))); }; };</pre></div></div> </li> <li id="section-65"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-65">¶</a> </div> <p>Bind all of an object's methods to that object. Useful for ensuring that all callbacks defined on an object belong to it. </p> </div> <div class="content"><div class='highlight'><pre> _.bindAll = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> funcs = slice.call(arguments, <span class="number">1</span>); <span class="keyword">if</span> (funcs.length === <span class="number">0</span>) <span class="keyword">throw</span> <span class="keyword">new</span> Error(<span class="string">"bindAll must be passed function names"</span>); each(funcs, <span class="keyword">function</span>(f) { obj[f] = _.bind(obj[f], obj); }); <span class="keyword">return</span> obj; };</pre></div></div> </li> <li id="section-66"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-66">¶</a> </div> <p>Memoize an expensive function by storing its results. </p> </div> <div class="content"><div class='highlight'><pre> _.memoize = <span class="keyword">function</span>(func, hasher) { <span class="keyword">var</span> memo = {}; hasher || (hasher = _.identity); <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">var</span> key = hasher.apply(<span class="keyword">this</span>, arguments); <span class="keyword">return</span> _.has(memo, key) ? memo[key] : (memo[key] = func.apply(<span class="keyword">this</span>, arguments)); }; };</pre></div></div> </li> <li id="section-67"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-67">¶</a> </div> <p>Delays a function for the given number of milliseconds, and then calls it with the arguments supplied. </p> </div> <div class="content"><div class='highlight'><pre> _.delay = <span class="keyword">function</span>(func, wait) { <span class="keyword">var</span> args = slice.call(arguments, <span class="number">2</span>); <span class="keyword">return</span> setTimeout(<span class="keyword">function</span>(){ <span class="keyword">return</span> func.apply(<span class="literal">null</span>, args); }, wait); };</pre></div></div> </li> <li id="section-68"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-68">¶</a> </div> <p>Defers a function, scheduling it to run after the current call stack has cleared. </p> </div> <div class="content"><div class='highlight'><pre> _.defer = <span class="keyword">function</span>(func) { <span class="keyword">return</span> _.delay.apply(_, [func, <span class="number">1</span>].concat(slice.call(arguments, <span class="number">1</span>))); };</pre></div></div> </li> <li id="section-69"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-69">¶</a> </div> <p>Returns a function, that, when invoked, will only be triggered at most once during a given window of time. Normally, the throttled function will run as much as it can, without ever going more than once per <code>wait</code> duration; but if you'd like to disable the execution on the leading edge, pass <code>{leading: false}</code>. To disable execution on the trailing edge, ditto. </p> </div> <div class="content"><div class='highlight'><pre> _.throttle = <span class="keyword">function</span>(func, wait, options) { <span class="keyword">var</span> context, args, result; <span class="keyword">var</span> timeout = <span class="literal">null</span>; <span class="keyword">var</span> previous = <span class="number">0</span>; options || (options = {}); <span class="keyword">var</span> later = <span class="keyword">function</span>() { previous = <span class="keyword">new</span> Date; timeout = <span class="literal">null</span>; result = func.apply(context, args); }; <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">var</span> now = <span class="keyword">new</span> Date; <span class="keyword">if</span> (!previous && options.leading === <span class="literal">false</span>) previous = now; <span class="keyword">var</span> remaining = wait - (now - previous); context = <span class="keyword">this</span>; args = arguments; <span class="keyword">if</span> (remaining <= <span class="number">0</span>) { clearTimeout(timeout); timeout = <span class="literal">null</span>; previous = now; result = func.apply(context, args); } <span class="keyword">else</span> <span class="keyword">if</span> (!timeout && options.trailing !== <span class="literal">false</span>) { timeout = setTimeout(later, remaining); } <span class="keyword">return</span> result; }; };</pre></div></div> </li> <li id="section-70"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-70">¶</a> </div> <p>Returns a function, that, as long as it continues to be invoked, will not be triggered. The function will be called after it stops being called for N milliseconds. If <code>immediate</code> is passed, trigger the function on the leading edge, instead of the trailing. </p> </div> <div class="content"><div class='highlight'><pre> _.debounce = <span class="keyword">function</span>(func, wait, immediate) { <span class="keyword">var</span> result; <span class="keyword">var</span> timeout = <span class="literal">null</span>; <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">var</span> context = <span class="keyword">this</span>, args = arguments; <span class="keyword">var</span> later = <span class="keyword">function</span>() { timeout = <span class="literal">null</span>; <span class="keyword">if</span> (!immediate) result = func.apply(context, args); }; <span class="keyword">var</span> callNow = immediate && !timeout; clearTimeout(timeout); timeout = setTimeout(later, wait); <span class="keyword">if</span> (callNow) result = func.apply(context, args); <span class="keyword">return</span> result; }; };</pre></div></div> </li> <li id="section-71"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-71">¶</a> </div> <p>Returns a function that will be executed at most one time, no matter how often you call it. Useful for lazy initialization. </p> </div> <div class="content"><div class='highlight'><pre> _.once = <span class="keyword">function</span>(func) { <span class="keyword">var</span> ran = <span class="literal">false</span>, memo; <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">if</span> (ran) <span class="keyword">return</span> memo; ran = <span class="literal">true</span>; memo = func.apply(<span class="keyword">this</span>, arguments); func = <span class="literal">null</span>; <span class="keyword">return</span> memo; }; };</pre></div></div> </li> <li id="section-72"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-72">¶</a> </div> <p>Returns the first function passed as an argument to the second, allowing you to adjust arguments, run code before and after, and conditionally execute the original function. </p> </div> <div class="content"><div class='highlight'><pre> _.wrap = <span class="keyword">function</span>(func, wrapper) { <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">var</span> args = [func]; push.apply(args, arguments); <span class="keyword">return</span> wrapper.apply(<span class="keyword">this</span>, args); }; };</pre></div></div> </li> <li id="section-73"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-73">¶</a> </div> <p>Returns a function that is the composition of a list of functions, each consuming the return value of the function that follows. </p> </div> <div class="content"><div class='highlight'><pre> _.compose = <span class="keyword">function</span>() { <span class="keyword">var</span> funcs = arguments; <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">var</span> args = arguments; <span class="keyword">for</span> (<span class="keyword">var</span> i = funcs.length - <span class="number">1</span>; i >= <span class="number">0</span>; i--) { args = [funcs[i].apply(<span class="keyword">this</span>, args)]; } <span class="keyword">return</span> args[<span class="number">0</span>]; }; };</pre></div></div> </li> <li id="section-74"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-74">¶</a> </div> <p>Returns a function that will only be executed after being called N times. </p> </div> <div class="content"><div class='highlight'><pre> _.after = <span class="keyword">function</span>(times, func) { <span class="keyword">return</span> <span class="keyword">function</span>() { <span class="keyword">if</span> (--times < <span class="number">1</span>) { <span class="keyword">return</span> func.apply(<span class="keyword">this</span>, arguments); } }; };</pre></div></div> </li> <li id="section-75"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-75">¶</a> </div> <h2>Object Functions</h2> </div> </li> <li id="section-76"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-76">¶</a> </div> </div> </li> <li id="section-77"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-77">¶</a> </div> <p>Retrieve the names of an object's properties. Delegates to <strong>ECMAScript 5</strong>'s native <code>Object.keys</code> </p> </div> <div class="content"><div class='highlight'><pre> _.keys = nativeKeys || <span class="keyword">function</span>(obj) { <span class="keyword">if</span> (obj !== Object(obj)) <span class="keyword">throw</span> <span class="keyword">new</span> TypeError(<span class="string">'Invalid object'</span>); <span class="keyword">var</span> keys = []; <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) <span class="keyword">if</span> (_.has(obj, key)) keys.push(key); <span class="keyword">return</span> keys; };</pre></div></div> </li> <li id="section-78"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-78">¶</a> </div> <p>Retrieve the values of an object's properties. </p> </div> <div class="content"><div class='highlight'><pre> _.values = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> values = []; <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) <span class="keyword">if</span> (_.has(obj, key)) values.push(obj[key]); <span class="keyword">return</span> values; };</pre></div></div> </li> <li id="section-79"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-79">¶</a> </div> <p>Convert an object into a list of <code>[key, value]</code> pairs. </p> </div> <div class="content"><div class='highlight'><pre> _.pairs = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> pairs = []; <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) <span class="keyword">if</span> (_.has(obj, key)) pairs.push([key, obj[key]]); <span class="keyword">return</span> pairs; };</pre></div></div> </li> <li id="section-80"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-80">¶</a> </div> <p>Invert the keys and values of an object. The values must be serializable. </p> </div> <div class="content"><div class='highlight'><pre> _.invert = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> result = {}; <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) <span class="keyword">if</span> (_.has(obj, key)) result[obj[key]] = key; <span class="keyword">return</span> result; };</pre></div></div> </li> <li id="section-81"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-81">¶</a> </div> <p>Return a sorted list of the function names available on the object. Aliased as <code>methods</code> </p> </div> <div class="content"><div class='highlight'><pre> _.functions = _.methods = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> names = []; <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) { <span class="keyword">if</span> (_.isFunction(obj[key])) names.push(key); } <span class="keyword">return</span> names.sort(); };</pre></div></div> </li> <li id="section-82"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-82">¶</a> </div> <p>Extend a given object with all the properties in passed-in object(s). </p> </div> <div class="content"><div class='highlight'><pre> _.extend = <span class="keyword">function</span>(obj) { each(slice.call(arguments, <span class="number">1</span>), <span class="keyword">function</span>(source) { <span class="keyword">if</span> (source) { <span class="keyword">for</span> (<span class="keyword">var</span> prop <span class="keyword">in</span> source) { obj[prop] = source[prop]; } } }); <span class="keyword">return</span> obj; };</pre></div></div> </li> <li id="section-83"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-83">¶</a> </div> <p>Return a copy of the object only containing the whitelisted properties. </p> </div> <div class="content"><div class='highlight'><pre> _.pick = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> copy = {}; <span class="keyword">var</span> keys = concat.apply(ArrayProto, slice.call(arguments, <span class="number">1</span>)); each(keys, <span class="keyword">function</span>(key) { <span class="keyword">if</span> (key <span class="keyword">in</span> obj) copy[key] = obj[key]; }); <span class="keyword">return</span> copy; };</pre></div></div> </li> <li id="section-84"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-84">¶</a> </div> <p>Return a copy of the object without the blacklisted properties. </p> </div> <div class="content"><div class='highlight'><pre> _.omit = <span class="keyword">function</span>(obj) { <span class="keyword">var</span> copy = {}; <span class="keyword">var</span> keys = concat.apply(ArrayProto, slice.call(arguments, <span class="number">1</span>)); <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) { <span class="keyword">if</span> (!_.contains(keys, key)) copy[key] = obj[key]; } <span class="keyword">return</span> copy; };</pre></div></div> </li> <li id="section-85"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-85">¶</a> </div> <p>Fill in a given object with default properties. </p> </div> <div class="content"><div class='highlight'><pre> _.defaults = <span class="keyword">function</span>(obj) { each(slice.call(arguments, <span class="number">1</span>), <span class="keyword">function</span>(source) { <span class="keyword">if</span> (source) { <span class="keyword">for</span> (<span class="keyword">var</span> prop <span class="keyword">in</span> source) { <span class="keyword">if</span> (obj[prop] === <span class="keyword">void</span> <span class="number">0</span>) obj[prop] = source[prop]; } } }); <span class="keyword">return</span> obj; };</pre></div></div> </li> <li id="section-86"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-86">¶</a> </div> <p>Create a (shallow-cloned) duplicate of an object. </p> </div> <div class="content"><div class='highlight'><pre> _.clone = <span class="keyword">function</span>(obj) { <span class="keyword">if</span> (!_.isObject(obj)) <span class="keyword">return</span> obj; <span class="keyword">return</span> _.isArray(obj) ? obj.slice() : _.extend({}, obj); };</pre></div></div> </li> <li id="section-87"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-87">¶</a> </div> <p>Invokes interceptor with the obj, and then returns obj. The primary purpose of this method is to "tap into" a method chain, in order to perform operations on intermediate results within the chain. </p> </div> <div class="content"><div class='highlight'><pre> _.tap = <span class="keyword">function</span>(obj, interceptor) { interceptor(obj); <span class="keyword">return</span> obj; };</pre></div></div> </li> <li id="section-88"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-88">¶</a> </div> <p>Internal recursive comparison function for <code>isEqual</code>. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> eq = <span class="keyword">function</span>(a, b, aStack, bStack) {</pre></div></div> </li> <li id="section-89"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-89">¶</a> </div> <p>Identical objects are equal. <code>0 === -0</code>, but they aren't identical. See the <a href="http://wiki.ecmascript.org/doku.php?id=harmony:egal">Harmony <code>egal</code> proposal</a>. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (a === b) <span class="keyword">return</span> a !== <span class="number">0</span> || <span class="number">1</span> / a == <span class="number">1</span> / b;</pre></div></div> </li> <li id="section-90"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-90">¶</a> </div> <p>A strict comparison is necessary because <code>null == undefined</code>. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (a == <span class="literal">null</span> || b == <span class="literal">null</span>) <span class="keyword">return</span> a === b;</pre></div></div> </li> <li id="section-91"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-91">¶</a> </div> <p>Unwrap any wrapped objects. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (a <span class="keyword">instanceof</span> _) a = a._wrapped; <span class="keyword">if</span> (b <span class="keyword">instanceof</span> _) b = b._wrapped;</pre></div></div> </li> <li id="section-92"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-92">¶</a> </div> <p>Compare <code>[[Class]]</code> names. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> className = toString.call(a); <span class="keyword">if</span> (className != toString.call(b)) <span class="keyword">return</span> <span class="literal">false</span>; <span class="keyword">switch</span> (className) {</pre></div></div> </li> <li id="section-93"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-93">¶</a> </div> <p>Strings, numbers, dates, and booleans are compared by value. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">case</span> <span class="string">'[object String]'</span>:</pre></div></div> </li> <li id="section-94"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-94">¶</a> </div> <p>Primitives and their corresponding object wrappers are equivalent; thus, <code>"5"</code> is equivalent to <code>new String("5")</code>. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">return</span> a == String(b); <span class="keyword">case</span> <span class="string">'[object Number]'</span>:</pre></div></div> </li> <li id="section-95"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-95">¶</a> </div> <p><code>NaN</code>s are equivalent, but non-reflexive. An <code>egal</code> comparison is performed for other numeric values. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">return</span> a != +a ? b != +b : (a == <span class="number">0</span> ? <span class="number">1</span> / a == <span class="number">1</span> / b : a == +b); <span class="keyword">case</span> <span class="string">'[object Date]'</span>: <span class="keyword">case</span> <span class="string">'[object Boolean]'</span>:</pre></div></div> </li> <li id="section-96"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-96">¶</a> </div> <p>Coerce dates and booleans to numeric primitive values. Dates are compared by their millisecond representations. Note that invalid dates with millisecond representations of <code>NaN</code> are not equivalent. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">return</span> +a == +b;</pre></div></div> </li> <li id="section-97"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-97">¶</a> </div> <p>RegExps are compared by their source patterns and flags. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">case</span> <span class="string">'[object RegExp]'</span>: <span class="keyword">return</span> a.source == b.source && a.global == b.global && a.multiline == b.multiline && a.ignoreCase == b.ignoreCase; } <span class="keyword">if</span> (<span class="keyword">typeof</span> a != <span class="string">'object'</span> || <span class="keyword">typeof</span> b != <span class="string">'object'</span>) <span class="keyword">return</span> <span class="literal">false</span>;</pre></div></div> </li> <li id="section-98"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-98">¶</a> </div> <p>Assume equality for cyclic structures. The algorithm for detecting cyclic structures is adapted from ES 5.1 section 15.12.3, abstract operation <code>JO</code>. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> length = aStack.length; <span class="keyword">while</span> (length--) {</pre></div></div> </li> <li id="section-99"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-99">¶</a> </div> <p>Linear search. Performance is inversely proportional to the number of unique nested structures. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (aStack[length] == a) <span class="keyword">return</span> bStack[length] == b; }</pre></div></div> </li> <li id="section-100"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-100">¶</a> </div> <p>Objects with different constructors are not equivalent, but <code>Object</code>s from different frames are. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> aCtor = a.constructor, bCtor = b.constructor; <span class="keyword">if</span> (aCtor !== bCtor && !(_.isFunction(aCtor) && (aCtor <span class="keyword">instanceof</span> aCtor) && _.isFunction(bCtor) && (bCtor <span class="keyword">instanceof</span> bCtor))) { <span class="keyword">return</span> <span class="literal">false</span>; }</pre></div></div> </li> <li id="section-101"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-101">¶</a> </div> <p>Add the first object to the stack of traversed objects. </p> </div> <div class="content"><div class='highlight'><pre> aStack.push(a); bStack.push(b); <span class="keyword">var</span> size = <span class="number">0</span>, result = <span class="literal">true</span>;</pre></div></div> </li> <li id="section-102"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-102">¶</a> </div> <p>Recursively compare objects and arrays. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (className == <span class="string">'[object Array]'</span>) {</pre></div></div> </li> <li id="section-103"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-103">¶</a> </div> <p>Compare array lengths to determine if a deep comparison is necessary. </p> </div> <div class="content"><div class='highlight'><pre> size = a.length; result = size == b.length; <span class="keyword">if</span> (result) {</pre></div></div> </li> <li id="section-104"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-104">¶</a> </div> <p>Deep compare the contents, ignoring non-numeric properties. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">while</span> (size--) { <span class="keyword">if</span> (!(result = eq(a[size], b[size], aStack, bStack))) <span class="keyword">break</span>; } } } <span class="keyword">else</span> {</pre></div></div> </li> <li id="section-105"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-105">¶</a> </div> <p>Deep compare objects. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> a) { <span class="keyword">if</span> (_.has(a, key)) {</pre></div></div> </li> <li id="section-106"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-106">¶</a> </div> <p>Count the expected number of properties. </p> </div> <div class="content"><div class='highlight'><pre> size++;</pre></div></div> </li> <li id="section-107"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-107">¶</a> </div> <p>Deep compare each member. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) <span class="keyword">break</span>; } }</pre></div></div> </li> <li id="section-108"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-108">¶</a> </div> <p>Ensure that both objects contain the same number of properties. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (result) { <span class="keyword">for</span> (key <span class="keyword">in</span> b) { <span class="keyword">if</span> (_.has(b, key) && !(size--)) <span class="keyword">break</span>; } result = !size; } }</pre></div></div> </li> <li id="section-109"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-109">¶</a> </div> <p>Remove the first object from the stack of traversed objects. </p> </div> <div class="content"><div class='highlight'><pre> aStack.pop(); bStack.pop(); <span class="keyword">return</span> result; };</pre></div></div> </li> <li id="section-110"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-110">¶</a> </div> <p>Perform a deep comparison to check if two objects are equal. </p> </div> <div class="content"><div class='highlight'><pre> _.isEqual = <span class="keyword">function</span>(a, b) { <span class="keyword">return</span> eq(a, b, [], []); };</pre></div></div> </li> <li id="section-111"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-111">¶</a> </div> <p>Is a given array, string, or object empty? An "empty" object has no enumerable own-properties. </p> </div> <div class="content"><div class='highlight'><pre> _.isEmpty = <span class="keyword">function</span>(obj) { <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> <span class="literal">true</span>; <span class="keyword">if</span> (_.isArray(obj) || _.isString(obj)) <span class="keyword">return</span> obj.length === <span class="number">0</span>; <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> obj) <span class="keyword">if</span> (_.has(obj, key)) <span class="keyword">return</span> <span class="literal">false</span>; <span class="keyword">return</span> <span class="literal">true</span>; };</pre></div></div> </li> <li id="section-112"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-112">¶</a> </div> <p>Is a given value a DOM element? </p> </div> <div class="content"><div class='highlight'><pre> _.isElement = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> !!(obj && obj.nodeType === <span class="number">1</span>); };</pre></div></div> </li> <li id="section-113"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-113">¶</a> </div> <p>Is a given value an array? Delegates to ECMA5's native Array.isArray </p> </div> <div class="content"><div class='highlight'><pre> _.isArray = nativeIsArray || <span class="keyword">function</span>(obj) { <span class="keyword">return</span> toString.call(obj) == <span class="string">'[object Array]'</span>; };</pre></div></div> </li> <li id="section-114"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-114">¶</a> </div> <p>Is a given variable an object? </p> </div> <div class="content"><div class='highlight'><pre> _.isObject = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> obj === Object(obj); };</pre></div></div> </li> <li id="section-115"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-115">¶</a> </div> <p>Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp. </p> </div> <div class="content"><div class='highlight'><pre> each([<span class="string">'Arguments'</span>, <span class="string">'Function'</span>, <span class="string">'String'</span>, <span class="string">'Number'</span>, <span class="string">'Date'</span>, <span class="string">'RegExp'</span>], <span class="keyword">function</span>(name) { _[<span class="string">'is'</span> + name] = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> toString.call(obj) == <span class="string">'[object '</span> + name + <span class="string">']'</span>; }; });</pre></div></div> </li> <li id="section-116"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-116">¶</a> </div> <p>Define a fallback version of the method in browsers (ahem, IE), where there isn't any inspectable "Arguments" type. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (!_.isArguments(arguments)) { _.isArguments = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> !!(obj && _.has(obj, <span class="string">'callee'</span>)); }; }</pre></div></div> </li> <li id="section-117"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-117">¶</a> </div> <p>Optimize <code>isFunction</code> if appropriate. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (<span class="keyword">typeof</span> (<span class="regexp">/./</span>) !== <span class="string">'function'</span>) { _.isFunction = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> <span class="keyword">typeof</span> obj === <span class="string">'function'</span>; }; }</pre></div></div> </li> <li id="section-118"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-118">¶</a> </div> <p>Is a given object a finite number? </p> </div> <div class="content"><div class='highlight'><pre> _.isFinite = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> isFinite(obj) && !isNaN(parseFloat(obj)); };</pre></div></div> </li> <li id="section-119"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-119">¶</a> </div> <p>Is the given value <code>NaN</code>? (NaN is the only number which does not equal itself). </p> </div> <div class="content"><div class='highlight'><pre> _.isNaN = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> _.isNumber(obj) && obj != +obj; };</pre></div></div> </li> <li id="section-120"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-120">¶</a> </div> <p>Is a given value a boolean? </p> </div> <div class="content"><div class='highlight'><pre> _.isBoolean = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> obj === <span class="literal">true</span> || obj === <span class="literal">false</span> || toString.call(obj) == <span class="string">'[object Boolean]'</span>; };</pre></div></div> </li> <li id="section-121"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-121">¶</a> </div> <p>Is a given value equal to null? </p> </div> <div class="content"><div class='highlight'><pre> _.isNull = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> obj === <span class="literal">null</span>; };</pre></div></div> </li> <li id="section-122"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-122">¶</a> </div> <p>Is a given variable undefined? </p> </div> <div class="content"><div class='highlight'><pre> _.isUndefined = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> obj === <span class="keyword">void</span> <span class="number">0</span>; };</pre></div></div> </li> <li id="section-123"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-123">¶</a> </div> <p>Shortcut function for checking if an object has a given property directly on itself (in other words, not on a prototype). </p> </div> <div class="content"><div class='highlight'><pre> _.has = <span class="keyword">function</span>(obj, key) { <span class="keyword">return</span> hasOwnProperty.call(obj, key); };</pre></div></div> </li> <li id="section-124"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-124">¶</a> </div> <h2>Utility Functions</h2> </div> </li> <li id="section-125"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-125">¶</a> </div> </div> </li> <li id="section-126"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-126">¶</a> </div> <p>Run Underscore.js in <em>noConflict</em> mode, returning the <code>_</code> variable to its previous owner. Returns a reference to the Underscore object. </p> </div> <div class="content"><div class='highlight'><pre> _.noConflict = <span class="keyword">function</span>() { root._ = previousUnderscore; <span class="keyword">return</span> <span class="keyword">this</span>; };</pre></div></div> </li> <li id="section-127"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-127">¶</a> </div> <p>Keep the identity function around for default iterators. </p> </div> <div class="content"><div class='highlight'><pre> _.identity = <span class="keyword">function</span>(value) { <span class="keyword">return</span> value; };</pre></div></div> </li> <li id="section-128"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-128">¶</a> </div> <p>Run a function <strong>n</strong> times. </p> </div> <div class="content"><div class='highlight'><pre> _.times = <span class="keyword">function</span>(n, iterator, context) { <span class="keyword">var</span> accum = Array(Math.max(<span class="number">0</span>, n)); <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>; i < n; i++) accum[i] = iterator.call(context, i); <span class="keyword">return</span> accum; };</pre></div></div> </li> <li id="section-129"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-129">¶</a> </div> <p>Return a random integer between min and max (inclusive). </p> </div> <div class="content"><div class='highlight'><pre> _.random = <span class="keyword">function</span>(min, max) { <span class="keyword">if</span> (max == <span class="literal">null</span>) { max = min; min = <span class="number">0</span>; } <span class="keyword">return</span> min + Math.floor(Math.random() * (max - min + <span class="number">1</span>)); };</pre></div></div> </li> <li id="section-130"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-130">¶</a> </div> <p>List of HTML entities for escaping. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> entityMap = { escape: { <span class="string">'&'</span>: <span class="string">'&amp;'</span>, <span class="string">'<'</span>: <span class="string">'&lt;'</span>, <span class="string">'>'</span>: <span class="string">'&gt;'</span>, <span class="string">'"'</span>: <span class="string">'&quot;'</span>, <span class="string">"'"</span>: <span class="string">'&#x27;'</span>, <span class="string">'/'</span>: <span class="string">'&#x2F;'</span> } }; entityMap.unescape = _.invert(entityMap.escape);</pre></div></div> </li> <li id="section-131"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-131">¶</a> </div> <p>Regexes containing the keys and values listed immediately above. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> entityRegexes = { escape: <span class="keyword">new</span> RegExp(<span class="string">'['</span> + _.keys(entityMap.escape).join(<span class="string">''</span>) + <span class="string">']'</span>, <span class="string">'g'</span>), unescape: <span class="keyword">new</span> RegExp(<span class="string">'('</span> + _.keys(entityMap.unescape).join(<span class="string">'|'</span>) + <span class="string">')'</span>, <span class="string">'g'</span>) };</pre></div></div> </li> <li id="section-132"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-132">¶</a> </div> <p>Functions for escaping and unescaping strings to/from HTML interpolation. </p> </div> <div class="content"><div class='highlight'><pre> _.each([<span class="string">'escape'</span>, <span class="string">'unescape'</span>], <span class="keyword">function</span>(method) { _[method] = <span class="keyword">function</span>(string) { <span class="keyword">if</span> (string == <span class="literal">null</span>) <span class="keyword">return</span> <span class="string">''</span>; <span class="keyword">return</span> (<span class="string">''</span> + string).replace(entityRegexes[method], <span class="keyword">function</span>(match) { <span class="keyword">return</span> entityMap[method][match]; }); }; });</pre></div></div> </li> <li id="section-133"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-133">¶</a> </div> <p>If the value of the named <code>property</code> is a function then invoke it with the <code>object</code> as context; otherwise, return it. </p> </div> <div class="content"><div class='highlight'><pre> _.result = <span class="keyword">function</span>(object, property) { <span class="keyword">if</span> (object == <span class="literal">null</span>) <span class="keyword">return</span> <span class="keyword">void</span> <span class="number">0</span>; <span class="keyword">var</span> value = object[property]; <span class="keyword">return</span> _.isFunction(value) ? value.call(object) : value; };</pre></div></div> </li> <li id="section-134"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-134">¶</a> </div> <p>Add your own custom functions to the Underscore object. </p> </div> <div class="content"><div class='highlight'><pre> _.mixin = <span class="keyword">function</span>(obj) { each(_.functions(obj), <span class="keyword">function</span>(name){ <span class="keyword">var</span> func = _[name] = obj[name]; _.prototype[name] = <span class="keyword">function</span>() { <span class="keyword">var</span> args = [<span class="keyword">this</span>._wrapped]; push.apply(args, arguments); <span class="keyword">return</span> result.call(<span class="keyword">this</span>, func.apply(_, args)); }; }); };</pre></div></div> </li> <li id="section-135"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-135">¶</a> </div> <p>Generate a unique integer id (unique within the entire client session). Useful for temporary DOM ids. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> idCounter = <span class="number">0</span>; _.uniqueId = <span class="keyword">function</span>(prefix) { <span class="keyword">var</span> id = ++idCounter + <span class="string">''</span>; <span class="keyword">return</span> prefix ? prefix + id : id; };</pre></div></div> </li> <li id="section-136"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-136">¶</a> </div> <p>By default, Underscore uses ERB-style template delimiters, change the following template settings to use alternative delimiters. </p> </div> <div class="content"><div class='highlight'><pre> _.templateSettings = { evaluate : <span class="regexp">/<%([\s\S]+?)%>/g</span>, interpolate : <span class="regexp">/<%=([\s\S]+?)%>/g</span>, escape : <span class="regexp">/<%-([\s\S]+?)%>/g</span> };</pre></div></div> </li> <li id="section-137"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-137">¶</a> </div> <p>When customizing <code>templateSettings</code>, if you don't want to define an interpolation, evaluation or escaping regex, we need one that is guaranteed not to match. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> noMatch = <span class="regexp">/(.)^/</span>;</pre></div></div> </li> <li id="section-138"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-138">¶</a> </div> <p>Certain characters need to be escaped so that they can be put into a string literal. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> escapes = { <span class="string">"'"</span>: <span class="string">"'"</span>, <span class="string">'\\'</span>: <span class="string">'\\'</span>, <span class="string">'\r'</span>: <span class="string">'r'</span>, <span class="string">'\n'</span>: <span class="string">'n'</span>, <span class="string">'\t'</span>: <span class="string">'t'</span>, <span class="string">'\u2028'</span>: <span class="string">'u2028'</span>, <span class="string">'\u2029'</span>: <span class="string">'u2029'</span> }; <span class="keyword">var</span> escaper = <span class="regexp">/\\|'|\r|\n|\t|\u2028|\u2029/g</span>;</pre></div></div> </li> <li id="section-139"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-139">¶</a> </div> <p>JavaScript micro-templating, similar to John Resig's implementation. Underscore templating handles arbitrary delimiters, preserves whitespace, and correctly escapes quotes within interpolated code. </p> </div> <div class="content"><div class='highlight'><pre> _.template = <span class="keyword">function</span>(text, data, settings) { <span class="keyword">var</span> render; settings = _.defaults({}, settings, _.templateSettings);</pre></div></div> </li> <li id="section-140"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-140">¶</a> </div> <p>Combine delimiters into one regular expression via alternation. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> matcher = <span class="keyword">new</span> RegExp([ (settings.escape || noMatch).source, (settings.interpolate || noMatch).source, (settings.evaluate || noMatch).source ].join(<span class="string">'|'</span>) + <span class="string">'|$'</span>, <span class="string">'g'</span>);</pre></div></div> </li> <li id="section-141"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-141">¶</a> </div> <p>Compile the template source, escaping string literals appropriately. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> index = <span class="number">0</span>; <span class="keyword">var</span> source = <span class="string">"__p+='"</span>; text.replace(matcher, <span class="keyword">function</span>(match, escape, interpolate, evaluate, offset) { source += text.slice(index, offset) .replace(escaper, <span class="keyword">function</span>(match) { <span class="keyword">return</span> <span class="string">'\\'</span> + escapes[match]; }); <span class="keyword">if</span> (escape) { source += <span class="string">"'+\n((__t=("</span> + escape + <span class="string">"))==null?'':_.escape(__t))+\n'"</span>; } <span class="keyword">if</span> (interpolate) { source += <span class="string">"'+\n((__t=("</span> + interpolate + <span class="string">"))==null?'':__t)+\n'"</span>; } <span class="keyword">if</span> (evaluate) { source += <span class="string">"';\n"</span> + evaluate + <span class="string">"\n__p+='"</span>; } index = offset + match.length; <span class="keyword">return</span> match; }); source += <span class="string">"';\n"</span>;</pre></div></div> </li> <li id="section-142"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-142">¶</a> </div> <p>If a variable is not specified, place data values in local scope. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">if</span> (!settings.variable) source = <span class="string">'with(obj||{}){\n'</span> + source + <span class="string">'}\n'</span>; source = <span class="string">"var __t,__p='',__j=Array.prototype.join,"</span> + <span class="string">"print=function(){__p+=__j.call(arguments,'');};\n"</span> + source + <span class="string">"return __p;\n"</span>; <span class="keyword">try</span> { render = <span class="keyword">new</span> Function(settings.variable || <span class="string">'obj'</span>, <span class="string">'_'</span>, source); } <span class="keyword">catch</span> (e) { e.source = source; <span class="keyword">throw</span> e; } <span class="keyword">if</span> (data) <span class="keyword">return</span> render(data, _); <span class="keyword">var</span> template = <span class="keyword">function</span>(data) { <span class="keyword">return</span> render.call(<span class="keyword">this</span>, data, _); };</pre></div></div> </li> <li id="section-143"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-143">¶</a> </div> <p>Provide the compiled function source as a convenience for precompilation. </p> </div> <div class="content"><div class='highlight'><pre> template.source = <span class="string">'function('</span> + (settings.variable || <span class="string">'obj'</span>) + <span class="string">'){\n'</span> + source + <span class="string">'}'</span>; <span class="keyword">return</span> template; };</pre></div></div> </li> <li id="section-144"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-144">¶</a> </div> <p>Add a "chain" function, which will delegate to the wrapper. </p> </div> <div class="content"><div class='highlight'><pre> _.chain = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> _(obj).chain(); };</pre></div></div> </li> <li id="section-145"> <div class="annotation"> <div class="pilwrap for-h2"> <a class="pilcrow" href="#section-145">¶</a> </div> <h2>OOP</h2> </div> </li> <li id="section-146"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-146">¶</a> </div> <p>If Underscore is called as a function, it returns a wrapped object that can be used OO-style. This wrapper holds altered versions of all the underscore functions. Wrapped objects may be chained. </p> </div> </li> <li id="section-147"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-147">¶</a> </div> <p>Helper function to continue chaining intermediate results. </p> </div> <div class="content"><div class='highlight'><pre> <span class="keyword">var</span> result = <span class="keyword">function</span>(obj) { <span class="keyword">return</span> <span class="keyword">this</span>._chain ? _(obj).chain() : obj; };</pre></div></div> </li> <li id="section-148"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-148">¶</a> </div> <p>Add all of the Underscore functions to the wrapper object. </p> </div> <div class="content"><div class='highlight'><pre> _.mixin(_);</pre></div></div> </li> <li id="section-149"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-149">¶</a> </div> <p>Add all mutator Array functions to the wrapper. </p> </div> <div class="content"><div class='highlight'><pre> each([<span class="string">'pop'</span>, <span class="string">'push'</span>, <span class="string">'reverse'</span>, <span class="string">'shift'</span>, <span class="string">'sort'</span>, <span class="string">'splice'</span>, <span class="string">'unshift'</span>], <span class="keyword">function</span>(name) { <span class="keyword">var</span> method = ArrayProto[name]; _.prototype[name] = <span class="keyword">function</span>() { <span class="keyword">var</span> obj = <span class="keyword">this</span>._wrapped; method.apply(obj, arguments); <span class="keyword">if</span> ((name == <span class="string">'shift'</span> || name == <span class="string">'splice'</span>) && obj.length === <span class="number">0</span>) <span class="keyword">delete</span> obj[<span class="number">0</span>]; <span class="keyword">return</span> result.call(<span class="keyword">this</span>, obj); }; });</pre></div></div> </li> <li id="section-150"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-150">¶</a> </div> <p>Add all accessor Array functions to the wrapper. </p> </div> <div class="content"><div class='highlight'><pre> each([<span class="string">'concat'</span>, <span class="string">'join'</span>, <span class="string">'slice'</span>], <span class="keyword">function</span>(name) { <span class="keyword">var</span> method = ArrayProto[name]; _.prototype[name] = <span class="keyword">function</span>() { <span class="keyword">return</span> result.call(<span class="keyword">this</span>, method.apply(<span class="keyword">this</span>._wrapped, arguments)); }; }); _.extend(_.prototype, {</pre></div></div> </li> <li id="section-151"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-151">¶</a> </div> <p>Start chaining a wrapped Underscore object. </p> </div> <div class="content"><div class='highlight'><pre> chain: <span class="keyword">function</span>() { <span class="keyword">this</span>._chain = <span class="literal">true</span>; <span class="keyword">return</span> <span class="keyword">this</span>; },</pre></div></div> </li> <li id="section-152"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-152">¶</a> </div> <p>Extracts the result from a wrapped and chained object. </p> </div> <div class="content"><div class='highlight'><pre> value: <span class="keyword">function</span>() { <span class="keyword">return</span> <span class="keyword">this</span>._wrapped; } }); }).call(<span class="keyword">this</span>);</pre></div></div> </li> </ul> </div> </body> </html>