Function.apply و Function.call در جاوااسکریپت

function myFunction(a, b) {
    return a * b;
}
myObject = myFunction.call(myObject, 10, 2);     // return 20

function myFunction(a, b) {
    return a * b;
}
myArray = [10, 2];
myObject = myFunction.apply(myObject, myArray);  //  return 2

var x = 10;
function f()
{
    alert(this.x);
}
f();

var x = 10;
var o = { x: 15 };
 
function f()
{
    alert(this.x);
}
f();  // ?
f.call(o); // ??

var x = 10;
var o = { x: 15 };
function f(message)
{
    alert(message);
    alert(this.x);
}
f("invoking f"); // invoking f 10
f.call(o, "invoking f via call"); // invoking f via call 15

var x = 10;
var o = { x: 15 };
function f(message)
{
    alert(message);
    alert(this.x);
}
 
f("invoking f");
f.apply(o, ["invoking f through apply"]);

var o = { x: 15 };
function f1(message1)
{
    alert(message1 + this.x);
}
function f2(message1, message2)
{
    alert(message1 + (this.x * this.x) + message2);
}
function g(object, func, args)
{
    func.apply(object, args);
}
g(o, f1, ["the value of x = "]);
g(o, f2, ["the value of x squared = ", ". Wow!"]);

function f(message)
{
    for(var i = 1; i < arguments.length; i++)
    {
        message += arguments[i];
    }
    alert(message);
}
// this will say "Hello"
f("H", "e", "l", "l", "o");

var o = { x: 15 };
function f(message1, message2)
{
    alert(message1 + (this.x * this.x) + message2);
}
function g(object, func)
{          
    // arguments[0] == object
    // arguments[1] == func 
     
    var args = []; // empty array
    // copy all other arguments we want to "pass through"
    for(var i = 2; i < arguments.length; i++)
    {
        args.push(arguments[i]);
    }
    func.apply(object, args);
}
g(o, f, "The value of x squared = ", ". Wow!");