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    ECMAScript 6 support in Mozilla Redirect 1

    ECMAScript 6 is the next version of the standard, code-named "Harmony" or "ES.next". Specification drafts can be found on the official wiki. If you wish to send feedback about the standard, do it on es-discuss.

    TC39 Consensus is marked by three levels:

    Consensus Ongoing Discussion Controversial

    These represent an estimate of the current state of consensus in TC39 of the features and their design. The three levels mean:

    • Consensus: no major remaining disagreements over the design
    • Ongoing discussion: the feature has consensus but there are aspects of the design that are still being discussed
    • Controversial: there remain significant disagreements about the design

    Features already supported in Firefox

    Syntax

    Feature Version Feature and Implementation Comment TC39 Consensus
    const JS 1.5 Not compliant with the current specification: scoped like var not let Consensus
    let (global scope) JS 1.7 Not compliant with the current specification Ongoing Discussion
    let (local scope) JS 1.7 Not compliant with the current specification Consensus
    Destructuring assignment JS 1.7 Not compliant with the current specification Consensus
    for...of statement Firefox 13   Consensus
    Iterators and generators ? Not compliant with the current specification Consensus
    Rest parameters Firefox 15   Consensus
    Default parameters Firefox 15   Consensus
    Spread operator of Array Firefox 16   Consensus
    Spread operator of Function calls Firefox 27   Consensus
    Arrow functions Firefox 22   Consensus
    Binary and octal integer literals Firefox 25 Binary: 0b010101 or 0B010101; Octal: 0o7170 or 0O7170 Consensus

    Standard library

    Feature Version Feature and Implementation Comment TC39 Consensus
    Map Firefox 13 A new type of collections Consensus
    Map Iteration Firefox 17 Iterable in for-of Consensus
    map.forEach Firefox 25   Consensus
    map.entries Firefox 20   Consensus
    map.keys Firefox 20   Consensus
    map.values Firefox 20   Consensus
    Set Firefox 13 A new type of collections Consensus
    Set Iteration Firefox 17 Iterable in for-of Consensus
    set.forEach Firefox 25   Consensus
    set.entries Firefox 24   Consensus
    set.keys Firefox 24   Consensus
    set.values Firefox 24   Consensus
    Array Iteration Firefox 13 Iterable in for-of Consensus
    Array.of() Firefox 25   Consensus
    array.find() Firefox 25   Consensus
    array.findIndex() Firefox 25   Consensus
    array.entries() Firefox 28   Consensus
    array.keys() Firefox 28   Consensus
    array.values() Firefox 28   Consensus
    WeakMap Firefox 6 A new type of collections Consensus
    weakmap.clear() Firefox 20   Controversial
    Proxy Firefox 18 Current implementation may differ from latest specification. Ongoing Discussion
    RegExp sticky (y) flag Firefox 3   Consensus
    Number.isNaN() Firefox 16   Consensus
    Number.isFinite() Firefox 16   Consensus
    Number.isInteger() Firefox 16   ?
    Number.parseInt() Firefox 25   ?
    Number.parseFloat() Firefox 25   ?
    Number.EPSILON Firefox 25 The smallest interval between two representable numbers. Consensus
    String.fromCodePoint() Firefox 29   Consensus
    string.codePointAt() Firefox 29   Consensus
    string.startsWith() Firefox 17   Consensus
    string.endsWith() Firefox 17   Consensus
    string.contains() Firefox 17   Consensus
    string.repeat() Firefox 24   Consensus
    Object.is Firefox 22   Ongoing Discussion
    Math.imul Firefox 20 C-like 32-bit integer multiplication Consensus
    New Math functions Firefox 25 log10, log2, log1p, expm1, cosh, sinh, tanh, acosh, asinh, atanh, hypot, trunc, sign ?
    Math.fround Firefox 26 Rounds to the nearest single-precision float (Float32) ?
    Promise Firefox 24 Behind the pref dom.promise.enabled up to Firefox 28.0 Ongoing Discussion

    Features not yet supported

    • is and isnt operator
    • Number.toInteger()
    • Module
      • Loader API
      • import syntax
      • export syntax
    • Symbol
    • class syntax
    • Computed property names
    • Template strings
    • WeakSet
    • array.fill()
    • Typed objects
    • Object.assign()
    • Object.setPrototypeOf()
    • Array.from()

    See also

    Document Tags and Contributors

    Contributors to this page: Sheppy
    Last updated by: Sheppy,