Function

JavaScript functions are objects. They can be defined using the Function constructor, like so:

var sum = new Function('a', 'b', 'return a + b;');

This is a (generally not recommended) alternative to the function literal (also known as function expression):

var sum = function (a, b) {
  return a + b;
};

Or, the more common function definition:

function sum(a, b) {
  return a + b;
}

The Function.prototype members

Property/Method	Description
apply(this_obj, params_array)	Allows you to call another function while overwriting the other function's this value. The first parameter that apply() accepts is the object to be bound to this inside the function and the second is an array of arguments to be send to the function being called. function whatIsIt(){ return this.toString(); } > var myObj = {}; > whatIsIt.apply(myObj); "[object Object]" > whatIsIt.apply(window); "[object Window]"
call(this_obj, p1, p2, p3, ...)...