callApply.js

function MyClass () {}
MyClass.prototype.doSomething = function (item1, item2, item3) {
	this.result = item1 + item2 + item3;
};

function MyComposedClass () {}
MyComposedClass.prototype.doSomethingElse = function () {
	MyClass.prototype.doSomething.apply(this, arguments);
}

var mCC = new MyComposedClass();
mCC.doSomethingElse(1, 2, 3);
console.log(mCC.result); // 6