JS Call and apply

function Add (A, b)  {      alert (a+b);  }   function Sub (A, b)  {      alert (a-b);  }    Add.call (Sub,3,1);   

Example 1

The meaning of Example 1 is to replace sub,add.call (sub,3,1) = = Add (3,1) with add, so the result is: alert (4); Note: The function in JS is actually an object, and the function name is a reference to a function object.

var ary=[3,1];   function Add (A, b)  {      alert (a+b);  }   function Sub (A, b)  {      alert (a-b);  }  Add.apply (sub,ary);

Example 2

The meaning in Example 2 is also to replace sub,add.apply (sub,ary) = = Add (3,1) with add, so the result is also: alert (4);

The common point of call and Applay:

1) are used to change the This keyword, such as add.call (sub,3,1) means to replace a sub with add

2) The first parameter in parentheses is the this value to be changed

Call and Apply differences:

The parameters in call are passed in by one, and the arguments in apply are in the form of an array.

JS Call and apply