JS In this usage example detailed

Source: Internet
Author: User
Tags closure

1. Point to Window

Global variables

1 Alert (this)//Back [object Window]

Global functions

1 2 3 4 function SayHello () {alert (this);} sayhello ();

2. Point to the object (in the global inside this point to window, within an object this point to the object, within the closure this point to window)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17-18 var user= "the window"; var box={User: ' The box ', Getthis:function () {return this.user}, Getthis2:function () {return function () {return this.us Er } } }; alert (this.user);//the Window alert (Box.getthis ());//the box alert (Box.getthis2 ()); The window (because the closure is used, here's this point to Window) alert (Box.getthis2 (). Call (box)); The box object is impersonating (this here is pointing to the box object)

3. Change the this point of the function with Apply,call

1 2 3 4 5 6 7 8 function sum (NUM1, num2) {return num1+num2} function box (NUM1, num2) {return sum.apply (this, [Num1, num2]);//this represents win Dow scope Box pretends sum to execute} console.log (Box (10,10)); 20

4. New Object

func tion person () {Console.log (this)//point this to a new empty object} var p = new person ();

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.