JavaScript function overloading

function-overloading.js

var def = function(functions, parent) {
	return function() {
		var types = [];
		var args = [];
		eachArg(arguments, function(i, elem) {
			args.push(elem);
			types.push(whatis(elem));
		});
		if(functions.hasOwnProperty(types.join())) {
			return functions[types.join()].apply(parent, args);
		} else {
			if (typeof functions === 'function')
				return functions.apply(parent, args);
			if (functions.hasOwnProperty('default'))
				return functions['default'].apply(parent, args);		
		}
	};
};

var eachArg = function(args, fn) {
	var i = 0;
	while (args.hasOwnProperty(i)) {
		if(fn !== undefined)
			fn(i, args[i]);
		i++;
	}
	return i-1;
};