Visual Studio has never supported JavaScript the way it supported .NET languages such as C# or VB.NET. While the Visual Studio 11 Beta does not close the gap completely, it does add numerous features intended to make JavaScript development easier such as significantly enhanced Intellisense, debugging support, editor functionality, and more.
The new JavaScript design time engine shares its base with IE’s JavaScript engine, providing better performance and consuming less memory. This also means that Visual Studio JavaScript syntax errors are identical to syntax errors displayed in IE. Unfortunately these errors may not be the same as errors displayed in other major browsers such as Firefox and Chrome due to slight differences in parsing.
JavaScript IntelliSense has been expanded through a variety of new features. It is now ECMAScript 5 compliant and rebuilds automatically (no more Ctrl Shift J). Script tags for JavaScript files also load IntelliSense content from the referenced files. Additionally, developers can add implicit references to files for JavaScript through the Options menu. This gives project-wide IntelliSense support for the referenced JavaScript files. Developers can write their own descriptive signature information for JavaScript functions with IntelliSense signature overloading.
Debugging support for JavaScript has been extended to allow opening remote extension-less JavaScript files in the editor. Developers can set breakpoints on individual statements in addition to complete lines, allowing debugging of compressed JavaScript files. The Dom Explorer and JavaScript Console are also supported when debugging with IE.
The Visual Studio editor now handles outlining, brace matching, brace highlighting, and Go to Definition(F12) natively. Validation and color coding for Regular expressions are also supported.
For a detailed list of new JavaScript changes, see the Microsoft web development tools group blog.
ECMAScript 5 is the fifth version of the ECMAScript language specification. JavaScript is the most widely used implementation of the ECMAScript specification.
You can read more about the Visual Studio 11 Beta on this Microsoft blog, or go directly to the Visual Studio 11 Beta download site.