IntelleSense is a pretty standard feature of any modern Integrated Development Environment (IDE). Visual Studio has the ability to display IntelleSense not only for the whole .Net framework but also for any libraries included in the solution and any custom code written in C#, VB or similar language. IntelliSense is not available for javascript files by default, partly because javascript is not build by a compiler. Fortunately it is quite easy to configure.
Firstly, create a new file called _references.js in the ‘Script’ folder of your project (note the intended leading underscore). Then add a reference for each file you require IntelliSense for like below;

/// <reference path="jquery-2.1.1.js" />
/// <reference path="knockout-3.2.0.debug.js" />
/// <reference path="your-custom-file.js" />

There is a shortcut to typing the references manually, simply drag and drop the file from the Solution Explorer into the editor pane and the reference will be added for you.

That’s basically it. Simple but useful.