JS's Call/apply/bind

Test code:

var a = 1; var obj = {     = 2;  } function Test (a) {    alert (a);    Alert (this. a);  }

1.test (3);

Results: 3,1

The This in the function points to the Window object

2.test.call (thisobj,param1,param2 ...);

The point of this in the Thisobj:test function

PARAM1,PARAM2: Parameters passed to the test function

3.test.call (null,3) or Test.call (undefined,3);

The results were: 1, 3;

When thisobj is undefined or null, this in test points to the window

4.test.call (1,3), or Test.call ("a", 3) or Test.call (false,3) or Test.call ([12],3) or Test.call (function () {},3) or Test.call (/ao/g,3);

The result is: 3,undefined

At this point the value of this is 1, "a", Flase,[12],function () {},/ao/g; there is no a attribute

5.test.call (obj,3);

The result is: 3,2

6.test.apply (Thisobj,[param1,param2 ...]);

In addition to giving the test arguments in array form, the other is the same as Test.call

7.test.bind (Thisobj,param1,pamra2 ...);

Bind () returns a new function, which is a copy of test, but the inside of this is a pointer to Thisobj

Source:

function (scope) {  varthis;   return function () {      fn.apply (scope);   }}

Case:

1.

var x = +; var foo = {    x: $        }varfunction(A, b) {    Console.log (  this. x,a,b);    } Bar (up); var nBar = Bar.bind (foo,4,5); NBar ();

Bar (print out): 100,1,2;this point to Widdow;

NBar () Print out: 200,4,5;this points to Foo, and NBar saves 4, 5 to the NBar parameter list when it is created

2.

var x = +; var foo = {    x: $    }varfunction(A, b) {    Console.log (  this. x,a,b);        Console.log (arguments);} Bar (up); var nBar = Bar.bind (foo,4,5); NBar (6,7);

Nbar execution: Arguments inside Saved 4,5,6,7

3.

JS's Call/apply/bind