Firefox 35 技術文件

{{ ReleaseChannelInfo("35", "35", "January 2015", "Aurora") }}

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Changes for Web developers

Developer Tools



  • The obsolete and non-conforming bottommargin, leftmargin, rightmargin and topmargin attributes of the <body> element have been activated in non-quirks mode (bug 95530).


  • The "temporal dead zone" for let declarations has been implemented. In conformance with ES6 let semantics, the following situations now throw errors. See also this newsgroup announcement and bug 1001090.
    • Redeclaring existing variables or arguments using let within the same scope in function bodies is now a syntax error.
    • Using a variable declared using let in function bodies before the declaration is reached and evaluated is now a runtime error.
  • ES6 Symbols (en-US) (only available in the Nightly channel) have been updated to conform with recent specification changes:
    • String(Symbol("1")) now no longer throws a TypeError; instead a string ("Symbol(1)") gets returned (bug 1058396).
  • The various TypedArray constructors now have as their [[Prototype]] a single function, denoted %TypedArray% in ES6 (but otherwise not directly exposed). Each typed array prototype now inherits from %TypedArray%.prototype. (%TypedArray% and %TypedArray%.prototype inherit from Function.prototype and Object.prototype, respectively, so that typed array constructors and instances still have the properties found on those objects.) Typed array function properties now reside on %TypedArray%.prototype and work on any typed array. See TypedArray and bug 896116 for more information.
  • ES6 semantics for prototype mutations using object literals have been implemented (bug 1061853).
    • Now only a single member notated as __proto__:value will mutate the [[Prototype]] in the object literal syntax.
    • Method members like __proto__() {} will not overwrite the [[Prototype]] anymore.



  • The dtls OpenType feature (via the CSS font-feature-settings (en-US) on the default stylesheet) is now applied automatically to MathML elements when positioning scripts over it (e.g. dotless i with mathematical hat).


No change.


No change.


Changes for add-on and Mozilla developers


  • The private _getTabForBrowser() method on the tabbrowser element has been deprecated. In its place, we've added a new, public, method called getTabForBrowser. This returns, predictably, the tab element that contains the specified browser.

Older versions