Bind.js

bindHelper.js

function foo(something){
	console.log( this.a, something );
    return this.a + something;
}

function bind(fn, obj) {
	return function() {
		return fn.apply(obj, arguments);
	};
}

var obj = {
	a: 1;
}

var bar = bind(foo, obj); // write this bind function.

var baz = bar(3); // 1 3
console.log(baz); // 4