In ECMAScript v3, these two methods are defined for the Function stereotype, and they both work the same way: you can call a Function just like you would any other object method. The following is easy to understand, first look at the code:

function Introduce(name,age)
{
    document.write("My name is "+name+".I am "+age);
}
var p=new People();
Introduce.call(p,"Windking",20);

As for the above code, Introduce is the method of p after the use of call. Do you understand? Using the call method, the above code is equivalent to this code:

function People(name,age)
{
    this.name=name;
    this.age=age;
    this.Introduce=function(){
document.write("My name is "+name+".I am "+age);
};
}

1. Share methods. First look at the code:

function Introduce(name,age)
{
        document.write("My name is "+name+".I am "+age);
}

This is a method of self-introduction. Now suppose we have a boy’s class and a girl’s class (I’m just going to demonstrate here, in practice, using a parent class of People), because their Introduce is the same, so we can share this method.

function Boy()
{
        this.BoyIntroduce=function(){
Introduce.call(this,name,age);
};
}

The same goes for Girl, so we can avoid writing code. Actually, this is a little far-fetched, because we could have written it as:

function Boy()
{
        this.BoyIntroduce=function(){
            Introduce(name,age);
}
}

But this time, if we use Apply, it will look a lot easier:

function Boy()
{
        this.BoyIntroduce=function(){
Introduce.apply(this,arguments);
};
}

Is it a lot easier? If the parameter is a lot of words, so is it not necessary to write so a dense string of parameters it!

2. Cross-domain invocation

See a simple example (for demonstration purposes only, no value whatsoever) :

function Boy(name,age)
{
        this.BoyIntroduce=function(){
            document.write("My name is "+name+".I am "+age);
}
}
function Girl(name,age)
{

}

This is a Boy and a Girl class, and then we write the following code:

Var b = new Boy (” Windking ”, 20); B.B oyIntroduce ();

Var g = new Girl (” Xuan ”, 22); Introduce the call (g, “Xuan”, 22).

3. True use — inheritance

All right, that’s a lot of little tricks, but here’s the most common use of call and apply, which is to construct inheritance.