The difference between the call and the Apply method in JS

I. Description of call and apply

1, Call,apply is a method of function.prototype, it is implemented within the JavaScript engine, because it belongs to the Function.prototype, each Function object instance (that is, each method) Have call,apply properties. since as a property of the method, the use of them is of course for the method, and these two methods are easy to confuse, because they work the same way, just different ways of using.

2, Syntax: Foo.call (this, arg1,arg2,arg3) = = Foo.apply (this, arguments) = = This.foo (arg1, arg2, arg3);

3, the same point: two methods produce the same effect.

4, different points: The method passed different parameters.

Second, the example code
<script type= "Text/javascript" >
function A () {
This.flag = ' A ';
This.tip = function () {
alert (This.flag);
};
}
function B () {
This.flag = ' B ';
}
var a = new A ();
var B = new B ();
A.tip.call (b);
A.tip.apply (b);
</script>

Iii. code interpretation (that is, apply and call role)

1, the instance code defines two functions A and b,a contain the flag attribute and the Tip attribute (this property assigns a function), B has a flag property.

2. Create objects A and b for A and B, respectively.

3, whether A.tip.call (b); and a.tip.apply (b); The result of the operation is a popup B.

4. from the results, you can see that call and apply both allow the B object to invoke the Tip method of the A object, and modify the current action object of this.

The difference between the call and the Apply method in JS