ECMA 6 Kangax Compatibility Results ## default function parameters - [x] basic functionality - [x] explicit undefined defers to the default - [x] defaults can refer to previous params - [x] arguments object interaction - [x] temporal dead zone - [x] separate scope - [x] new Function() support ## rest parameters - [x] basic functionality - [x] function 'length' property - [x] arguments object interaction - [x] can't be used in setters - [x] new Function() support ## spread (...) operator - [x] with arrays, in function calls - [x] with arrays, in array literals - [x] with sparse arrays, in function calls - [x] with sparse arrays, in array literals - [x] with strings, in function calls - [x] with strings, in array literals - [ ] with astral plane strings, in function calls - [ ] with astral plane strings, in array literals - [ ] with generator instances, in calls - [ ] with generator instances, in arrays - [x] with generic iterables, in calls - [x] with generic iterables, in arrays - [x] with instances of iterables, in calls - [x] with instances of iterables, in arrays - [x] spreading non-iterables is a runtime error ## object literal extensions - [x] computed properties - [x] shorthand properties - [x] shorthand methods - [x] string-keyed shorthand methods - [x] computed shorthand methods - [x] computed accessors ## for..of loops - [x] with arrays - [x] with sparse arrays - [x] with strings - [ ] with astral plane strings - [ ] with generator instances - [x] with generic iterables - [x] with instances of generic iterables - [x] iterator closing, break - [x] iterator closing, throw ## octal and binary literals - [x] octal literals - [x] binary literals - [x] octal supported by Number() - [x] binary supported by Number() ## template strings - [ ] basic functionality - [x] toString conversion - [x] tagged template strings - [x] passed array is frozen - [x] line break normalisation ## RegExp "y" and "u" flags - [ ] "y" flag - [ ] "y" flag, lastIndex - [ ] "u" flag - [ ] "u" flag, Unicode code point escapes ## destructuring, declarations - [x] with arrays - [x] with sparse arrays - [x] with strings - [ ] with astral plane strings - [ ] with generator instances - [x] with generic iterables - [x] with instances of generic iterables - [x] iterator closing - [x] trailing commas in iterable patterns - [x] with objects - [x] object destructuring with primitives - [x] trailing commas in object patterns - [x] throws on null and undefined - [x] computed properties - [x] multiples in a single var statement - [x] nested - [x] in for-in loop heads - [x] in for-of loop heads - [x] in catch heads - [x] rest - [x] defaults - [x] defaults, let temporal dead zone ## destructuring, assignment - [x] with arrays - [x] with sparse arrays - [x] with strings - [ ] with astral plane strings - [ ] with generator instances - [x] with generic iterables - [x] with instances of generic iterables - [x] iterator closing - [x] iterable destructuring expression - [x] chained iterable destructuring - [ ] trailing commas in iterable patterns - [x] with objects - [x] object destructuring with primitives - [x] trailing commas in object patterns - [x] object destructuring expression - [ ] parenthesised left-hand-side is a syntax error - [x] chained object destructuring - [x] throws on null and undefined - [x] computed properties - [x] nested - [x] rest - [x] nested rest - [x] empty patterns - [x] defaults ## destructuring, parameters - [x] with arrays - [x] with sparse arrays - [x] with strings - [ ] with astral plane strings - [ ] with generator instances - [x] with generic iterables - [x] with instances of generic iterables - [x] iterator closing - [x] trailing commas in iterable patterns - [x] with objects - [x] object destructuring with primitives - [x] trailing commas in object patterns - [x] throws on null and undefined - [x] computed properties - [x] nested - [x] 'arguments' interaction - [x] new Function() support - [x] in parameters, function 'length' property - [x] rest - [x] empty patterns - [x] defaults - [x] defaults, separate scope - [x] defaults, new Function() support ## Unicode code point escapes - [x] in strings - [x] in identifiers ## new.target - [x] in constructors - [x] assignment is an early error ## const - [x] basic support - [x] is block-scoped - [x] redefining a const is an error - [x] temporal dead zone - [x] basic support (strict mode) - [x] is block-scoped (strict mode) - [x] redefining a const (strict mode) - [x] temporal dead zone (strict mode) ## let - [x] basic support - [x] is block-scoped - [x] for-loop statement scope - [x] temporal dead zone - [x] for-loop iteration scope - [x] basic support (strict mode) - [x] is block-scoped (strict mode) - [x] for-loop statement scope (strict mode) - [x] temporal dead zone (strict mode) - [x] for-loop iteration scope (strict mode) - [ ] block-level function declaration ## arrow functions - [x] 0 parameters - [x] 1 parameter, no brackets - [x] multiple parameters - [x] lexical "this" binding - [x] "this" unchanged by call or apply - [x] can't be bound, can be curried - [x] lexical "arguments" binding - [x] no line break between params and => - [x] correct precedence - [x] no "prototype" property - [x] lexical "super" binding in constructors - [x] lexical "super" binding in methods - [x] lexical "new.target" binding ## class - [x] class statement - [x] is block-scoped - [x] class expression - [x] anonymous class - [x] constructor - [x] prototype methods - [x] string-keyed methods - [x] computed prototype methods - [x] static methods - [x] computed static methods - [x] accessor properties - [x] computed accessor properties - [x] static accessor properties - [x] computed static accessor properties - [ ] class name is lexically scoped - [x] computed names, temporal dead zone - [x] methods aren't enumerable - [ ] implicit strict mode - [x] constructor requires new - [ ] extends - [ ] extends expressions - [ ] extends null - [ ] new.target ## super - [x] statement in constructors - [x] expression in constructors - [x] in methods, property access - [x] in methods, method calls - [x] method calls use correct "this" binding - [ ] constructor calls use correct "new.target" binding - [x] is statically bound - [x] super() invokes the correct constructor ## generators - [ ] basic functionality - [ ] generator function expressions - [ ] correct "this" binding - [x] can't use "this" with new - [ ] sending - [ ] %GeneratorPrototype% - [ ] %GeneratorPrototype%.constructor - [ ] %GeneratorPrototype%.throw - [ ] %GeneratorPrototype%.return - [ ] yield operator precedence - [ ] yield *, arrays - [ ] yield *, sparse arrays - [ ] yield *, strings - [ ] yield *, astral plane strings - [ ] yield *, generator instances - [ ] yield *, generic iterables - [ ] yield *, instances of iterables - [ ] yield * on non-iterables is a runtime error - [ ] yield *, iterator closing - [ ] yield *, iterator closing via throw() - [ ] shorthand generator methods - [ ] string-keyed shorthand generator methods - [ ] computed shorthand generators - [ ] shorthand generator methods, classes - [ ] computed shorthand generators, classes ## typed arrays - [ ] Int8Array - [ ] Uint8Array - [ ] Uint8ClampedArray - [ ] Int16Array - [ ] Uint16Array - [ ] Int32Array - [ ] Uint32Array - [ ] Float32Array - [ ] Float64Array - [ ] DataView (Int8) - [ ] DataView (Uint8) - [ ] DataView (Int16) - [ ] DataView (Uint16) - [ ] DataView (Int32) - [ ] DataView (Uint32) - [ ] DataView (Float32) - [ ] DataView (Float64) - [ ] ArrayBuffer[Symbol.species] - [ ] constructors require new - [ ] constructors accept generic iterables - [ ] correct prototype chains - [ ] %TypedArray%.from - [ ] %TypedArray%.of - [ ] %TypedArray%.prototype.subarray - [ ] %TypedArray%.prototype.join - [ ] %TypedArray%.prototype.indexOf - [ ] %TypedArray%.prototype.lastIndexOf - [ ] %TypedArray%.prototype.slice - [ ] %TypedArray%.prototype.every - [ ] %TypedArray%.prototype.filter - [ ] %TypedArray%.prototype.forEach - [ ] %TypedArray%.prototype.map - [ ] %TypedArray%.prototype.reduce - [ ] %TypedArray%.prototype.reduceRight - [ ] %TypedArray%.prototype.reverse - [ ] %TypedArray%.prototype.some - [ ] %TypedArray%.prototype.sort - [ ] %TypedArray%.prototype.copyWithin - [ ] %TypedArray%.prototype.find - [ ] %TypedArray%.prototype.findIndex - [ ] %TypedArray%.prototype.fill - [ ] %TypedArray%.prototype.keys - [ ] %TypedArray%.prototype.values - [ ] %TypedArray%.prototype.entries - [ ] %TypedArray%.prototype[Symbol.iterator] - [ ] %TypedArray%[Symbol.species] ## Map - [x] basic functionality - [x] constructor arguments - [x] constructor requires new - [x] constructor accepts null - [x] constructor invokes set - [x] iterator closing - [x] Map.prototype.set returns this - [x] -0 key converts to +0 - [x] Map.prototype.size - [x] Map.prototype.delete - [x] Map.prototype.clear - [x] Map.prototype.forEach - [x] Map.prototype.keys - [x] Map.prototype.values - [x] Map.prototype.entries - [x] Map.prototype[Symbol.iterator] - [x] Map iterator prototype chain - [x] Map[Symbol.species] ## Set - [x] basic functionality - [x] constructor arguments - [x] constructor requires new - [x] constructor accepts null - [x] constructor invokes add - [x] iterator closing - [x] Set.prototype.add returns this - [x] -0 key converts to +0 - [x] Set.prototype.size - [x] Set.prototype.delete - [x] Set.prototype.clear - [x] Set.prototype.forEach - [x] Set.prototype.keys - [x] Set.prototype.values - [x] Set.prototype.entries - [x] Set.prototype[Symbol.iterator] - [x] Set iterator prototype chain - [x] Set[Symbol.species] ## WeakMap - [ ] basic functionality - [ ] constructor arguments - [ ] constructor requires new - [ ] constructor accepts null - [ ] constructor invokes set - [ ] frozen objects as keys - [ ] iterator closing - [ ] WeakMap.prototype.set returns this - [ ] WeakMap.prototype.delete - [ ] no WeakMap.prototype.clear method ## WeakSet - [ ] basic functionality - [ ] constructor arguments - [ ] constructor requires new - [ ] constructor accepts null - [ ] constructor invokes add - [ ] iterator closing - [ ] WeakSet.prototype.add returns this - [ ] WeakSet.prototype.delete - [ ] no WeakSet.prototype.clear method ## Proxy - [x] constructor requires new - [x] "get" handler - [x] "get" handler, instances of proxies - [x] "set" handler - [ ] "set" handler, instances of proxies - [x] "has" handler - [x] "has" handler, instances of proxies - [x] "deleteProperty" handler - [x] "getOwnPropertyDescriptor" handler - [x] "defineProperty" handler - [x] "getPrototypeOf" handler - [x] "setPrototypeOf" handler - [x] "isExtensible" handler - [x] "preventExtensions" handler - [x] "enumerate" handler - [x] "ownKeys" handler - [x] "apply" handler - [x] "construct" handler - [x] Proxy.revocable - [x] Array.isArray support - [x] JSON.stringify support ## Reflect - [x] Reflect.get - [x] Reflect.set - [x] Reflect.has - [x] Reflect.deleteProperty - [x] Reflect.getOwnPropertyDescriptor - [x] Reflect.defineProperty - [x] Reflect.getPrototypeOf - [x] Reflect.setPrototypeOf - [x] Reflect.isExtensible - [x] Reflect.preventExtensions - [x] Reflect.enumerate - [x] Reflect.ownKeys, string keys - [x] Reflect.ownKeys, symbol keys - [x] Reflect.apply - [x] Reflect.construct - [x] Reflect.construct sets new.target meta property - [x] Reflect.construct creates instance from newTarget argument ## Promise - [ ] basic functionality - [ ] constructor requires new - [ ] Promise.all - [ ] Promise.all, generic iterables - [ ] Promise.race - [ ] Promise.race, generic iterables - [ ] Promise[Symbol.species] ## Symbol - [x] basic functionality - [x] typeof support - [x] symbol keys are hidden to pre-ES6 code - [x] Object.defineProperty support - [ ] cannot coerce to string or number - [x] can convert with String() - [x] new Symbol() throws - [ ] Object(symbol) - [x] JSON.stringify ignores symbols - [x] global symbol registry ## well-known symbols - [ ] Symbol.hasInstance - [x] Symbol.isConcatSpreadable - [x] Symbol.iterator, existence - [ ] Symbol.iterator, arguments object - [x] Symbol.species, existence - [x] Symbol.species, Array.prototype.concat - [x] Symbol.species, Array.prototype.filter - [x] Symbol.species, Array.prototype.map - [x] Symbol.species, Array.prototype.slice - [x] Symbol.species, Array.prototype.splice - [ ] Symbol.species, RegExp.prototype[Symbol.split] - [x] Symbol.replace - [x] Symbol.search - [x] Symbol.split - [x] Symbol.match - [ ] Symbol.match, RegExp constructor - [x] Symbol.match, String.prototype.startsWith - [x] Symbol.match, String.prototype.endsWith - [x] Symbol.match, String.prototype.includes - [x] Symbol.toPrimitive - [x] Symbol.toStringTag - [x] Symbol.toStringTag, misc. built-ins - [ ] Symbol.unscopables ## Object static methods - [x] Object.assign - [x] Object.is - [x] Object.getOwnPropertySymbols - [x] Object.setPrototypeOf ## function "name" property - [x] function statements - [x] function expressions - [x] new Function - [x] bound functions - [x] variables (function) - [x] object methods (function) - [x] accessor properties - [x] shorthand methods - [x] shorthand methods (no lexical binding) - [x] symbol-keyed methods - [x] class statements - [x] class expressions - [x] variables (class) - [x] object methods (class) - [x] class prototype methods - [x] class static methods - [x] isn't writable, is configurable ## String static methods - [x] String.raw - [x] String.fromCodePoint ## String.prototype methods - [x] String.prototype.codePointAt - [x] String.prototype.normalize - [x] String.prototype.repeat - [x] String.prototype.startsWith - [x] String.prototype.endsWith - [x] String.prototype.includes - [x] String.prototype[Symbol.iterator] - [x] String iterator prototype chain ## RegExp.prototype properties - [ ] RegExp.prototype.flags - [x] RegExp.prototype[Symbol.match] - [x] RegExp.prototype[Symbol.replace] - [x] RegExp.prototype[Symbol.split] - [x] RegExp.prototype[Symbol.search] - [x] RegExp[Symbol.species] ## Array static methods - [x] Array.from, array-like objects - [ ] Array.from, generator instances - [x] Array.from, generic iterables - [x] Array.from, instances of generic iterables - [x] Array.from map function, array-like objects - [ ] Array.from map function, generator instances - [x] Array.from map function, generic iterables - [x] Array.from map function, instances of iterables - [x] Array.from, iterator closing - [x] Array.of - [x] Array[Symbol.species] ## Array.prototype methods - [x] Array.prototype.copyWithin - [x] Array.prototype.find - [x] Array.prototype.findIndex - [x] Array.prototype.fill - [x] Array.prototype.keys - [x] Array.prototype.values - [x] Array.prototype.entries - [x] Array.prototype[Symbol.iterator] - [x] Array iterator prototype chain - [ ] Array.prototype[Symbol.unscopables] ## Number properties - [x] Number.isFinite - [x] Number.isInteger - [x] Number.isSafeInteger - [x] Number.isNaN - [x] Number.EPSILON - [x] Number.MIN_SAFE_INTEGER - [x] Number.MAX_SAFE_INTEGER ## Math methods - [x] Math.clz32 - [x] Math.imul - [x] Math.sign - [x] Math.log10 - [x] Math.log2 - [x] Math.log1p - [x] Math.expm1 - [x] Math.cosh - [x] Math.sinh - [x] Math.tanh - [x] Math.acosh - [x] Math.asinh - [x] Math.atanh - [x] Math.trunc - [x] Math.fround - [x] Math.cbrt - [x] Math.hypot ## Array is subclassable - [ ] length property (accessing) - [ ] length property (setting) - [ ] correct prototype chain - [ ] Array.isArray support - [ ] Array.prototype.concat - [ ] Array.prototype.filter - [ ] Array.prototype.map - [ ] Array.prototype.slice - [ ] Array.prototype.splice - [ ] Array.from - [ ] Array.of ## RegExp is subclassable - [ ] basic functionality - [ ] correct prototype chain - [ ] RegExp.prototype.exec - [ ] RegExp.prototype.test ## Function is subclassable - [ ] can be called - [ ] correct prototype chain - [ ] can be used with "new" - [ ] Function.prototype.call - [ ] Function.prototype.apply - [ ] Function.prototype.bind ## Promise is subclassable - [ ] basic functionality - [ ] correct prototype chain - [ ] Promise.all - [ ] Promise.race ## miscellaneous subclassables - [ ] Boolean is subclassable - [ ] Number is subclassable - [ ] String is subclassable - [ ] Map is subclassable - [ ] Set is subclassable ## prototype of bound functions - [x] basic functions - [x] generator functions - [x] arrow functions - [x] classes - [ ] subclasses ## Proxy, internal 'get' calls - [ ] ToPrimitive - [ ] CreateListFromArrayLike - [ ] instanceof operator - [ ] HasBinding - [ ] CreateDynamicFunction - [ ] ClassDefinitionEvaluation - [x] IteratorComplete, IteratorValue - [ ] ToPropertyDescriptor - [x] Object.assign - [ ] Object.defineProperties - [x] Function.prototype.bind - [x] Error.prototype.toString - [x] String.raw - [ ] RegExp constructor - [ ] RegExp.prototype.flags - [ ] RegExp.prototype.test - [ ] RegExp.prototype[Symbol.match] - [ ] RegExp.prototype[Symbol.replace] - [ ] RegExp.prototype[Symbol.search] - [ ] RegExp.prototype[Symbol.split] - [x] Array.from - [ ] Array.prototype.concat - [x] Array.prototype iteration methods - [x] Array.prototype.pop - [x] Array.prototype.reverse - [x] Array.prototype.shift - [x] Array.prototype.splice - [x] Array.prototype.toString - [x] JSON.stringify - [ ] Promise resolve functions - [ ] String.prototype.match - [ ] String.prototype.replace - [ ] String.prototype.search - [ ] String.prototype.split - [ ] Date.prototype.toJSON ## Proxy, internal 'set' calls - [x] Object.assign - [x] Array.from - [x] Array.of - [x] Array.prototype.copyWithin - [x] Array.prototype.fill - [x] Array.prototype.pop - [x] Array.prototype.push - [x] Array.prototype.reverse - [x] Array.prototype.shift - [x] Array.prototype.splice - [x] Array.prototype.unshift ## Proxy, internal 'defineProperty' calls - [ ] [[Set]] - [x] SetIntegrityLevel ## Proxy, internal 'deleteProperty' calls - [x] Array.prototype.copyWithin - [x] Array.prototype.pop - [x] Array.prototype.reverse - [x] Array.prototype.shift - [x] Array.prototype.splice - [x] Array.prototype.unshift ## Proxy, internal 'getOwnPropertyDescriptor' calls - [ ] [[Set]] - [x] Object.assign - [x] Object.prototype.hasOwnProperty - [x] Function.prototype.bind ## Proxy, internal 'ownKeys' calls - [x] SetIntegrityLevel - [x] TestIntegrityLevel - [x] SerializeJSONObject ## Object static methods accept primitives - [x] Object.getPrototypeOf - [x] Object.getOwnPropertyDescriptor - [x] Object.getOwnPropertyNames - [x] Object.seal - [x] Object.freeze - [x] Object.preventExtensions - [x] Object.isSealed - [x] Object.isFrozen - [x] Object.isExtensible - [x] Object.keys ## own property order - [x] for..in - [x] Object.keys - [x] Object.getOwnPropertyNames - [x] Object.assign - [x] JSON.stringify - [x] JSON.parse - [x] Reflect.ownKeys, string key order - [x] Reflect.ownKeys, symbol key order ## miscellaneous - [x] no escaped reserved words as identifiers - [x] duplicate property names in strict mode - [x] no semicolon needed after do-while - [ ] no assignments allowed in for-in head - [ ] accessors aren't constructors - [x] Invalid Date - [ ] RegExp constructor can alter flags - [ ] built-in prototypes are not instances - [x] function 'length' is configurable - [ ] String.prototype case methods, Unicode support ## non-strict function semantics - [ ] hoisted block-level function declaration - [x] labeled function statements - [ ] function statements in if-statement clauses ## __proto__ in object literals - [ ] basic support - [x] multiple __proto__ is an error - [ ] not a computed property - [ ] not a shorthand property - [ ] not a shorthand method ## Object.prototype.__proto__ - [ ] get prototype - [ ] set prototype - [ ] absent from Object.create(null) - [ ] present in hasOwnProperty() - [ ] correct property descriptor - [ ] present in Object.getOwnPropertyNames() ## String.prototype HTML methods - [ ] existence - [ ] tags' names are lowercase - [ ] quotes in arguments are escaped - [x] RegExp.prototype.compile ## RegExp syntax extensions - [x] hyphens in character sets - [x] invalid character escapes - [x] invalid control-character escapes - [x] invalid Unicode escapes - [x] invalid hexadecimal escapes - [x] incomplete patterns and quantifiers - [x] octal escape sequences - [x] invalid backreferences become octal escapes - [x] HTML-style comments