Polyfill for Function.prototype.bind

Function.prototype.bind.js

(function(){
	if (!Function.prototype.bind) {
		var Empty = function(){};
		Function.prototype.bind = function bind(that) { // .length is 1
			var target = this;
			if (typeof target !== "function") {
				throw new TypeError("Function.prototype.bind called on incompatible " + target);
			}
			var args = Array.prototype.slice.call(arguments, 1); // for normal call
			var binder = function () {
				if (this instanceof bound) {
					var result = target.apply(
						this,
						args.concat(Array.prototype.slice.call(arguments))
					);
					if (Object(result) === result) {
						return result;
					}
					return this;
				} else {
					return target.apply(
						that,
						args.concat(Array.prototype.slice.call(arguments))
					);
				}
			};
			var boundLength = Math.max(0, target.length - args.length);
			var boundArgs = [];
			for (var i = 0; i < boundLength; i++) {
				boundArgs.push("$" + i);
			}
			var bound = Function("binder", "return function(" + boundArgs.join(",") + "){return binder.apply(this,arguments)}")(binder);

			if (target.prototype) {
				Empty.prototype = target.prototype;
				bound.prototype = new Empty();
				// Clean up dangling references.
				Empty.prototype = null;
			}
			return bound;
		};
	}
})();