This of JavaScript

Global scope of this

 this = = window   //truethis. A  = 8  window.a//  8

This of the general function

function thistest () {   returnthis = = = Window   //true  function  thistest () {   ' use strict '   returnthis = = = Undefined   //true

The this in a function as an object method

 var o  = {  x:1,  y:2,  f:function() {        returnthis. X}}O.F ()  //x    as the object method function in this, This object is pointing to

On this on the object prototype chain

var o  = {f:functionthis. A+ this. B}}var obj= = 90  = ten; OBJ.F ()  //The This   on the prototype chain, pointing to obj

This in the constructor

function fuc () {   this. A = PNs;}  var New fuc (); F.A    // Panax   Notoginseng

function   func () {   this. A =n;     return 1;} var New func (); FUNC.A   // 65

function   funct () {   this. A =n;     return {x:1};} var New funct (); Funct.x   // 1

When you create an object from the new constructor
1  There is no return or return at the time of the basic type. returns this. (This prototype points to the function where this is located)
2  Returns the object type, returning the object as the return value

Call/apply method and this

 function   Add (c) { return  this . A+this . B+c}  var  o = { A:2,b:4}add.call (o,  4) // 10 call the first parameter passed in the object to be used as this, followed by the arguments in the function argument list, separated by commas 
 
   

function Add1 (c) {  returnthis. A+ this. B +C}var o1 = {A:2,b:4} Add1.apply (o,[4])  //    Apply the first parameter passed in the object to be used as this, followed by the arguments passed in the function argument list, passed in as an array

function fuc (x, y) {
Console.info (X,y,this)
}

Fuc.call (1,7,6); 7 6 Number

Fuc.call (NULL); Undefined undefined Window

Fuc.apply (NULL); Undefined undefined Window

Fuc.call (undefined); Undefined undefined Window

Fuc.apply (undefined); Undefined undefined window in general mode, call,apply incoming null,undefined point to the window

Bind method with this

function Z () {   returnthis. a}; var g = Z.bind ({a: "*"}); g ()   //"the" """var o = {a:4, f:z,g:g };O.F ()  ///4   function As Object method, this points to O object, all O.F () is 4//  "89 The  bind method binds Z () to the point of this in {a: "_"}

This of JavaScript