Is there a tool to remove unused methods in javascript?

Question

I've got a collection of javascript files from a 3rd party, and I'd like to remove all the unused methods to get size down to a more reasonable level.

Does anyone know of a tool that does this for Javascript? At the very least give a list of unused/used methods, so I could do the manually trimming? This would be in addition to running something like the YUI Javascript compressor tool...

Otherwise my thought is to write a perl script to attempt to help me do this.

Answer 1

No. Because you can "use" methods in insanely dynamic ways like this.

obj[prompt("Gimme a method name.")]();

Answer 2

Unless the library author kept track of dependencies and provided a way to download the minimal code [e.g. MooTools Core download], it will be hard to to identify 'unused' functions.

The problem is that JS is a dynamic language and there are several ways to call a function.

E.g. you may have a method like

function test() 
{
   //
}

You can call it like

   test();

   var hello = i > 1 ? 'test' : 'xyz';
   hello();

   window[hello]();

Answer 3

Check out JSCoverage . Generates code coverage statistics that show which lines of a program have been executed (and which have been missed).