Function.introspect.js is a small library that interrogates a function to return its name, argument names and source code (if not native).

Use it like this:

function add(a, b) { return a + b; }
var finfo = Function.introspect(add);
// finfo => {
//	name: 'add',
//	args: 'a,b',
//	argNames: ['a','b'],
//	code: 'return a+b;',
//	isNative: false
// }

Compatibility: IE 6-8, Firefox 3-3.5, Safari 3-4, Chrome 3, node.js.