New in JavaScript 1.8.5

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The following is a changelog for JavaScript 1.8.5. This version was included in Firefox 4.

New features in JavaScript 1.8.5

New functions

Function Description
Object.create() Creates a new object with the specified prototype object and properties. bug 492840
Object.defineProperty() Adds the named property described by a given descriptor to an object.
Object.defineProperties() Adds the named properties described by the given descriptors to an object.
Object.getOwnPropertyDescriptor() Returns a property descriptor for a named property on an object. bug 505587
Object.keys() Returns an array of all enumerable properties on an object. bug 307791
Object.getOwnPropertyNames() Returns an array of all enumerable and non-enumerable properties on an object. bug 518663
Object.preventExtensions() Prevents any extensions of an object. bug 492849
Object.isExtensible() Determines if extending of an object is allowed. bug 492849
Object.seal() Prevents other code from deleting properties of an object. bug 492845
Object.isSealed() Determines if an object is sealed. bug 492845
Object.freeze() Freezes an object: other code can't delete or change any properties. bug 492844
Object.isFrozen() Determines if an object was frozen. bug 492844
Array.isArray() Checks if a variable is an array. bug 510537
Date.prototype.toJSON() Returns a JSON format string for a Date object.
Function.prototype.bind() Creates a new function that, when called, itself calls this function in the context provided (with a given sequence of arguments). bug 429507

New ECMAScript5 features

Other standardization work

Various non-standard syntaxes for defining getters and setters have been removed; ECMAScript 5 defined syntax has not been changed. These were all pretty esoteric and rarely used; if this affects you, see this blog post for details.

New objects

Object Description
Old Proxy API Offers support for creating Object and Function proxies that enable meta-programming in JavaScript.

Changed functionality in JavaScript 1.8.5