underscore.js

(function() {

  var root = this;

  var previousUnderscore = root._;

  var breaker = {};

  var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;

  var slice            = ArrayProto.slice,
      unshift          = ArrayProto.unshift,
      toString         = ObjProto.toString,
      hasOwnProperty   = ObjProto.hasOwnProperty;

  var
    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;

  var _ = function(obj) { return new wrapper(obj); };

  if (typeof module !== 'undefined' && module.exports) {
    module.exports = _;
    _._ = _;
  } else {

    root['_'] = _;
  }

  _.VERSION = '1.2.0';

  var each = _.each = _.forEach = function(obj, iterator, context) {
    if (obj == null) return;
    if (nativeForEach && obj.forEach === nativeForEach) {
      obj.forEach(iterator, context);
    } else if (obj.length === +obj.length) {
      for (var i = 0, l = obj.length; i < l; i++) {
        if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;
      }
    } else {
      for (var key in obj) {
        if (hasOwnProperty.call(obj, key)) {
          if (iterator.call(context, obj[key], key, obj) === breaker) return;
        }
      }
    }
  };

  _.map = function(obj, iterator, context) {
    var results = [];
    if (obj == null) return results;
    if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
    each(obj, function(value, index, list) {
      results[results.length] = iterator.call(context, value, index, list);
    });
    return results;
  };

  _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
    var initial = memo !== void 0;
    if (obj == null) obj = [];
    if (nativeReduce && obj.reduce === nativeReduce) {
      if (context) iterator = _.bind(iterator, context);
      return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
    }
    each(obj, function(value, index, list) {
      if (!initial) {
        memo = value;
        initial = true;
      } else {
        memo = iterator.call(context, memo, value, index, list);
      }
    });
    if (!initial) throw new TypeError("Reduce of empty array with no initial value");
    return memo;
  };

  _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
    if (obj == null) obj = [];
    if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
      if (context) iterator = _.bind(iterator, context);
      return memo !== void 0 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
    }
    var reversed = (_.isArray(obj) ? obj.slice() : _.toArray(obj)).reverse();
    return _.reduce(reversed, iterator, memo, context);
  };

  _.find = _.detect = function(obj, iterator, context) {
    var result;
    any(obj, function(value, index, list) {
      if (iterator.call(context, value, index, list)) {
        result = value;
        return true;
      }
    });
    return result;
  };

  _.filter = _.select = function(obj, iterator, context) {
    var results = [];
    if (obj == null) return results;
    if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
    each(obj, function(value, index, list) {
      if (iterator.call(context, value, index, list)) results[results.length] = value;
    });
    return results;
  };

  _.reject = function(obj, iterator, context) {
    var results = [];
    if (obj == null) return results;
    each(obj, function(value, index, list) {
      if (!iterator.call(context, value, index, list)) results[results.length] = value;
    });
    return results;
  };

  _.every = _.all = function(obj, iterator, context) {
    var result = true;
    if (obj == null) return result;
    if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
    each(obj, function(value, index, list) {
      if (!(result = result && iterator.call(context, value, index, list))) return breaker;
    });
    return result;
  };

  var any = _.some = _.any = function(obj, iterator, context) {
    iterator = iterator || _.identity;
    var result = false;
    if (obj == null) return result;
    if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
    each(obj, function(value, index, list) {
      if (result |= iterator.call(context, value, index, list)) return breaker;
    });
    return !!result;
  };

  _.include = _.contains = function(obj, target) {
    var found = false;
    if (obj == null) return found;
    if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
    any(obj, function(value) {
      if (found = value === target) return true;
    });
    return found;
  };

  _.invoke = function(obj, method) {
    var args = slice.call(arguments, 2);
    return _.map(obj, function(value) {
      return (method.call ? method || value : value[method]).apply(value, args);
    });
  };

  _.pluck = function(obj, key) {
    return _.map(obj, function(value){ return value[key]; });
  };

  _.max = function(obj, iterator, context) {
    if (!iterator && _.isArray(obj)) return Math.max.apply(Math, obj);
    if (!iterator && _.isEmpty(obj)) return -Infinity;
    var result = {computed : -Infinity};
    each(obj, function(value, index, list) {
      var computed = iterator ? iterator.call(context, value, index, list) : value;
      computed >= result.computed && (result = {value : value, computed : computed});
    });
    return result.value;
  };

  _.min = function(obj, iterator, context) {
    if (!iterator && _.isArray(obj)) return Math.min.apply(Math, obj);
    if (!iterator && _.isEmpty(obj)) return Infinity;
    var result = {computed : Infinity};
    each(obj, function(value, index, list) {
      var computed = iterator ? iterator.call(context, value, index, list) : value;
      computed < result.computed && (result = {value : value, computed : computed});
    });
    return result.value;
  };

  _.shuffle = function(obj) {
    var shuffled = [], rand;
    each(obj, function(value, index, list) {
      if (index == 0) {
        shuffled[0] = value;
      } else {
        rand = Math.floor(Math.random() * (index + 1));
        shuffled[index] = shuffled[rand];
        shuffled[rand] = value;
      }
    });
    return shuffled;
  };

  _.sortBy = function(obj, iterator, context) {
    return _.pluck(_.map(obj, function(value, index, list) {
      return {
        value : value,
        criteria : iterator.call(context, value, index, list)
      };
    }).sort(function(left, right) {
      var a = left.criteria, b = right.criteria;
      return a < b ? -1 : a > b ? 1 : 0;
    }), 'value');
  };

  _.groupBy = function(obj, iterator) {
    var result = {};
    each(obj, function(value, index) {
      var key = iterator(value, index);
      (result[key] || (result[key] = [])).push(value);
    });
    return result;
  };

  _.sortedIndex = function(array, obj, iterator) {
    iterator || (iterator = _.identity);
    var low = 0, high = array.length;
    while (low < high) {
      var mid = (low + high) >> 1;
      iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;
    }
    return low;
  };

  _.toArray = function(iterable) {
    if (!iterable)                return [];
    if (iterable.toArray)         return iterable.toArray();
    if (_.isArray(iterable))      return slice.call(iterable);
    if (_.isArguments(iterable))  return slice.call(iterable);
    return _.values(iterable);
  };

  _.size = function(obj) {
    return _.toArray(obj).length;
  };

  _.first = _.head = function(array, n, guard) {
    return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
  };

  _.initial = function(array, n, guard) {
    return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
  };

  _.last = function(array, n, guard) {
    return (n != null) && !guard ? slice.call(array, array.length - n) : array[array.length - 1];
  };

  _.rest = _.tail = function(array, index, guard) {
    return slice.call(array, (index == null) || guard ? 1 : index);
  };

  _.compact = function(array) {
    return _.filter(array, function(value){ return !!value; });
  };

  _.flatten = function(array) {
    return _.reduce(array, function(memo, value) {
      if (_.isArray(value)) return memo.concat(_.flatten(value));
      memo[memo.length] = value;
      return memo;
    }, []);
  };

  _.without = function(array) {
    return _.difference(array, slice.call(arguments, 1));
  };

  _.uniq = _.unique = function(array, isSorted, iterator) {
    var initial = iterator ? _.map(array, iterator) : array;
    var result = [];
    _.reduce(initial, function(memo, el, i) {
      if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) {
        memo[memo.length] = el;
        result[result.length] = array[i];
      }
      return memo;
    }, []);
    return result;
  };

  _.union = function() {
    return _.uniq(_.flatten(arguments));
  };

  _.intersection = _.intersect = function(array) {
    var rest = slice.call(arguments, 1);
    return _.filter(_.uniq(array), function(item) {
      return _.every(rest, function(other) {
        return _.indexOf(other, item) >= 0;
      });
    });
  };

  _.difference = function(array, other) {
    return _.filter(array, function(value){ return !_.include(other, value); });
  };

  _.zip = function() {
    var args = slice.call(arguments);
    var length = _.max(_.pluck(args, 'length'));
    var results = new Array(length);
    for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);
    return results;
  };

  _.indexOf = function(array, item, isSorted) {
    if (array == null) return -1;
    var i, l;
    if (isSorted) {
      i = _.sortedIndex(array, item);
      return array[i] === item ? i : -1;
    }
    if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
    for (i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
    return -1;
  };

  _.lastIndexOf = function(array, item) {
    if (array == null) return -1;
    if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
    var i = array.length;
    while (i--) if (array[i] === item) return i;
    return -1;
  };

  _.range = function(start, stop, step) {
    if (arguments.length <= 1) {
      stop = start || 0;
      start = 0;
    }
    step = arguments[2] || 1;

    var len = Math.max(Math.ceil((stop - start) / step), 0);
    var idx = 0;
    var range = new Array(len);

    while(idx < len) {
      range[idx++] = start;
      start += step;
    }

    return range;
  };

  _.bind = function(func, obj) {
    if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
    var args = slice.call(arguments, 2);
    return function() {
      return func.apply(obj, args.concat(slice.call(arguments)));
    };
  };

  _.bindAll = function(obj) {
    var funcs = slice.call(arguments, 1);
    if (funcs.length == 0) funcs = _.functions(obj);
    each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
    return obj;
  };

  _.memoize = function(func, hasher) {
    var memo = {};
    hasher || (hasher = _.identity);
    return function() {
      var key = hasher.apply(this, arguments);
      return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
    };
  };

  _.delay = function(func, wait) {
    var args = slice.call(arguments, 2);
    return setTimeout(function(){ return func.apply(func, args); }, wait);
  };

  _.defer = function(func) {
    return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
  };

  var limit = function(func, wait, debounce) {
    var timeout;
    return function() {
      var context = this, args = arguments;
      var throttler = function() {
        timeout = null;
        func.apply(context, args);
      };
      if (debounce) clearTimeout(timeout);
      if (debounce || !timeout) timeout = setTimeout(throttler, wait);
    };
  };

  _.throttle = function(func, wait) {
    return limit(func, wait, false);
  };

  _.debounce = function(func, wait) {
    return limit(func, wait, true);
  };

  _.once = function(func) {
    var ran = false, memo;
    return function() {
      if (ran) return memo;
      ran = true;
      return memo = func.apply(this, arguments);
    };
  };

  _.wrap = function(func, wrapper) {
    return function() {
      var args = [func].concat(slice.call(arguments));
      return wrapper.apply(this, args);
    };
  };

  _.compose = function() {
    var funcs = slice.call(arguments);
    return function() {
      var args = slice.call(arguments);
      for (var i = funcs.length - 1; i >= 0; i--) {
        args = [funcs[i].apply(this, args)];
      }
      return args[0];
    };
  };

  _.after = function(times, func) {
    return function() {
      if (--times < 1) { return func.apply(this, arguments); }
    };
  };

  _.keys = nativeKeys || function(obj) {
    if (obj !== Object(obj)) throw new TypeError('Invalid object');
    var keys = [];
    for (var key in obj) if (hasOwnProperty.call(obj, key)) keys[keys.length] = key;
    return keys;
  };

  _.values = function(obj) {
    return _.map(obj, _.identity);
  };

  _.functions = _.methods = function(obj) {
    var names = [];
    for (var key in obj) {
      if (_.isFunction(obj[key])) names.push(key);
    }
    return names.sort();
  };

  _.extend = function(obj) {
    each(slice.call(arguments, 1), function(source) {
      for (var prop in source) {
        if (source[prop] !== void 0) obj[prop] = source[prop];
      }
    });
    return obj;
  };

  _.defaults = function(obj) {
    each(slice.call(arguments, 1), function(source) {
      for (var prop in source) {
        if (obj[prop] == null) obj[prop] = source[prop];
      }
    });
    return obj;
  };

  _.clone = function(obj) {
    return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
  };

  _.tap = function(obj, interceptor) {
    interceptor(obj);
    return obj;
  };

  function eq(a, b, stack) {

    if (a === b) return a !== 0 || 1 / a == 1 / b;

    if (a == null) return a === b;

    var typeA = typeof a;
    if (typeA != typeof b) return false;

    if (!a != !b) return false;

    if (_.isNaN(a)) return _.isNaN(b);

    var isStringA = _.isString(a), isStringB = _.isString(b);
    if (isStringA || isStringB) return isStringA && isStringB && String(a) == String(b);

    var isNumberA = _.isNumber(a), isNumberB = _.isNumber(b);
    if (isNumberA || isNumberB) return isNumberA && isNumberB && +a == +b;

    var isBooleanA = _.isBoolean(a), isBooleanB = _.isBoolean(b);
    if (isBooleanA || isBooleanB) return isBooleanA && isBooleanB && +a == +b;

    var isDateA = _.isDate(a), isDateB = _.isDate(b);
    if (isDateA || isDateB) return isDateA && isDateB && a.getTime() == b.getTime();

    var isRegExpA = _.isRegExp(a), isRegExpB = _.isRegExp(b);
    if (isRegExpA || isRegExpB) {

      return isRegExpA && isRegExpB &&
             a.source == b.source &&
             a.global == b.global &&
             a.multiline == b.multiline &&
             a.ignoreCase == b.ignoreCase;
    }

    if (typeA != 'object') return false;

    if (a._chain) a = a._wrapped;
    if (b._chain) b = b._wrapped;

    if (_.isFunction(a.isEqual)) return a.isEqual(b);

    var length = stack.length;
    while (length--) {

      if (stack[length] == a) return true;
    }

    stack.push(a);
    var size = 0, result = true;
    if (a.length === +a.length || b.length === +b.length) {

      size = a.length;
      result = size == b.length;
      if (result) {

        while (size--) {

          if (!(result = size in a == size in b && eq(a[size], b[size], stack))) break;
        }
      }
    } else {

      for (var key in a) {
        if (hasOwnProperty.call(a, key)) {

          size++;

          if (!(result = hasOwnProperty.call(b, key) && eq(a[key], b[key], stack))) break;
        }
      }

      if (result) {
        for (key in b) {
          if (hasOwnProperty.call(b, key) && !size--) break;
        }
        result = !size;
      }
    }

    stack.pop();
    return result;
  }

  _.isEqual = function(a, b) {
    return eq(a, b, []);
  };

  _.isEmpty = function(obj) {
    if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
    for (var key in obj) if (hasOwnProperty.call(obj, key)) return false;
    return true;
  };

  _.isElement = function(obj) {
    return !!(obj && obj.nodeType == 1);
  };

  _.isArray = nativeIsArray || function(obj) {
    return toString.call(obj) === '[object Array]';
  };

  _.isObject = function(obj) {
    return obj === Object(obj);
  };

  _.isArguments = function(obj) {
    return !!(obj && hasOwnProperty.call(obj, 'callee'));
  };

  _.isFunction = function(obj) {
    return !!(obj && obj.constructor && obj.call && obj.apply);
  };

  _.isString = function(obj) {
    return !!(obj === '' || (obj && obj.charCodeAt && obj.substr));
  };

  _.isNumber = function(obj) {
    return !!(obj === 0 || (obj && obj.toExponential && obj.toFixed));
  };

  _.isNaN = function(obj) {
    return obj !== obj;
  };

  _.isBoolean = function(obj) {
    return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
  };

  _.isDate = function(obj) {
    return !!(obj && obj.getTimezoneOffset && obj.setUTCFullYear);
  };

  _.isRegExp = function(obj) {
    return !!(obj && obj.test && obj.exec && (obj.ignoreCase || obj.ignoreCase === false));
  };

  _.isNull = function(obj) {
    return obj === null;
  };

  _.isUndefined = function(obj) {
    return obj === void 0;
  };

  _.noConflict = function() {
    root._ = previousUnderscore;
    return this;
  };

  _.identity = function(value) {
    return value;
  };

  _.times = function (n, iterator, context) {
    for (var i = 0; i < n; i++) iterator.call(context, i);
  };

  _.escape = function(string) {
    return (''+string).replace(/&(?!\w+;|#\d+;|#x[\da-f]+;)/gi, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&#x27;').replace(/\//g,'&#x2F;');
  };

  _.mixin = function(obj) {
    each(_.functions(obj), function(name){
      addToWrapper(name, _[name] = obj[name]);
    });
  };

  var idCounter = 0;
  _.uniqueId = function(prefix) {
    var id = idCounter++;
    return prefix ? prefix + id : id;
  };

  _.templateSettings = {
    evaluate    : /<%([\s\S]+?)%>/g,
    interpolate : /<%=([\s\S]+?)%>/g,
    escape      : /<%-([\s\S]+?)%>/g
  };

  _.template = function(str, data) {
    var c  = _.templateSettings;
    var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +
      'with(obj||{}){__p.push(\'' +
      str.replace(/\\/g, '\\\\')
         .replace(/'/g, "\\'")
         .replace(c.escape, function(match, code) {
           return "',_.escape(" + code.replace(/\\'/g, "'") + "),'";
         })
         .replace(c.interpolate, function(match, code) {
           return "'," + code.replace(/\\'/g, "'") + ",'";
         })
         .replace(c.evaluate || null, function(match, code) {
           return "');" + code.replace(/\\'/g, "'")
                              .replace(/[\r\n\t]/g, ' ') + "__p.push('";
         })
         .replace(/\r/g, '\\r')
         .replace(/\n/g, '\\n')
         .replace(/\t/g, '\\t')
         + "');}return __p.join('');";
    var func = new Function('obj', tmpl);
    return data ? func(data) : func;
  };

  var wrapper = function(obj) { this._wrapped = obj; };

  _.prototype = wrapper.prototype;

  var result = function(obj, chain) {
    return chain ? _(obj).chain() : obj;
  };

  var addToWrapper = function(name, func) {
    wrapper.prototype[name] = function() {
      var args = slice.call(arguments);
      unshift.call(args, this._wrapped);
      return result(func.apply(_, args), this._chain);
    };
  };

  _.mixin(_);

  each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
    var method = ArrayProto[name];
    wrapper.prototype[name] = function() {
      method.apply(this._wrapped, arguments);
      return result(this._wrapped, this._chain);
    };
  });

  each(['concat', 'join', 'slice'], function(name) {
    var method = ArrayProto[name];
    wrapper.prototype[name] = function() {
      return result(method.apply(this._wrapped, arguments), this._chain);
    };
  });

  wrapper.prototype.chain = function() {
    this._chain = true;
    return this;
  };

  wrapper.prototype.value = function() {
    return this._wrapped;
  };

})();