Javascript: Function.Apply()

Allows you to apply a method of another object in the context of a different object (the calling object).

var result = function.apply(thisArg[, argsArray]);

You can assign a different this object when calling an existing function. this refers to the current object, the calling object. With apply, you can write a method once and then inherit it in another object, without having to rewrite the method for the new object.