Windows Internet Explorer 8 introduced native JavaScript Object Notation (JSON) support for JavaScript objects and accessor support for DOM objects. In addition to improved JavaScript performance,Windows Internet Explorer 9 added support for many more ECMAScript Language Specification, 5th edition features. Internet Explorer 10 introduces support for Typed Arrays and ECMAScript 5 (ES5) strict mode. For more information, see JavaScript Version Information

ECMAScript 5

There are a number of important ECMAScript 5 features implemented in Internet Explorer 9, including the following:

Internet Explorer 9 also corrects several issues present in the previous implementations of JavaScript in Windows Internet Explorer. For more information, see "Enhanced Scripting in IE9: ECMAScript 5 Support and More".

In this section


ES5 strict mode

ECMAScript is the emerging standard for JavaScript, defined by the ECMA-262 specification. The fifth edition was published in December 2009, and adds strict mode for more robust error checking.

Typed arrays

You can use typed arrays to handle binary data from sources such as network protocols, binary file formats, and raw graphics buffers. Typed arrays can also be used to manage in-memory binary data with well-known byte layouts.


API Reference

JavaScript Language Reference

Samples and tutorials

JavaScript Fundamentals
Advanced JavaScript

Internet Explorer Test Drive demos

ECMAScript 5 Arrays
ECMAScript5 Breakout
ECMAScript 5 Tile Switch Game
Web Worker Harness for test262

IEBlog posts

Spring Forward: Advancing Historical Date and Time Calculations on the Web
Building World-ready Applications in JavaScript Becoming a Reality
Advances in JavaScript Performance in IE10 and Windows 8
Diagnosing JavaScript Errors Faster with Error.stack
Evolving ECMAScript
test262: Industry JavaScript Standards Test Available
Exploring ECMAScript 5 with a Simple Game of Poker
IE9’s Document Modes and JavaScript
Asynchronous Programming in JavaScript with “Promises”
ECMAScript 5 Part 2: Array Extras
ECMAScript 5 Part 1: Reusable Code
Enhanced Scripting in IE9: ECMAScript 5 Support and More
The New JavaScript Engine in Internet Explorer 9


ECMAScript Language Specification, 5th edition