On Vue responsive principle, publish subscribe mode and observer mode

メSerendipity 2021-08-08 18:32:25
vue responsive principle publish subscribe

One .Vue Responsive principle

First of all, we need to understand several concepts :

Data responsive : Data model is only common Javascript object , And when we modify the data , The view will be updated , Avoid the tedious DOM operation , Improve development efficiency .

Two way binding : Data change , View change , And the data changed , We can use v-model Create a two-way data binding on the form .

Data driven is Vue One of the most unique features : In the development process, we only need to focus on the data itself , Don't care how the data is rendered to the view .

vue2.X The response principle in is based on defineProperty, compatible IE8 Above version , The core principle code is as follows :

 let data={
let vm={}
function proxyData(data){
// Execute when getting value 
return data[key]
// Execute when setting the value 
vm.msg // obtain (get Method ) hello
vm.msg='hello World' // Set new attribute values and render to the page (set Method )
vm.msg //hello World 

vue3.X The response principle in is based on Proxy, Listen directly to the object , Not attributes ,ES6 Newly added ,IE I won't support it , Performance is optimized by the browser , Performance ratio defineProperty It is better to , Compared with the words of code defineProperty Be concise , There is no need to loop through the values of multiple attributes .

 let data={
// simulation Vue example 
let vm=new Proxy(data,{
// Functions that perform proxy behavior 
// When accessing vm Members of the group will perform 
return target[key]
if(target[key] === newValue){
// test 
vm.msg='Hello World'

Two . Publish subscribe mode and observer mode

1. Release / A subscription model
This concept is a little abstract , Here is an example to illustrate , Parents are more concerned about their children's grades , Ask your child if his grades come out every day , Suppose you can subscribe to your child's grades in your child's class , Once the test results come out , It is equivalent to triggering an event , Finally, the teacher of the class informed the parents in the form of text message ,

You don't need to ask your child if his grades come out every day , Parents are subscribers to events , The teacher is the publisher of the event , The child's class can be imagined as the center of an event .vue Custom events in are based on publishing / Subscription mode . Let's simulate the operation mechanism of publish subscribe mode :

// Event trigger 
 class EventEmitter(){
// Initialize object { 'click':[fn1,fn2],'change':[fn] }
// Registration events 
this.subs[eventType] = this.subs[eventType] || []
// Triggering event 
this.subs[eventType].forEach(handler => {
// test 

let em =new EventEmitter()
em.$emit('click') // Print the results click1,click2

Two . Observer mode

The difference between observer mode and subscription mode is that there is no event center , Only publishers and subscribers , And publishers need to know the existence of subscribers .

Concept :

The observer --Watcher

update(): When the event occurs , Specific things to do .

Publisher --Dep

subs Array : Store all observers

addSub(): Add observers

notify(): When an event occurs , Call all the observers update() Method

// Publisher - The goal is 
 class Dep{
constructor() {
// Record all subscribers 
// Add subscribers 
if(sub && sub.update){
// Issue notice 
// subscriber - The observer 
 class Watcher{
// test 
let dep=new Dep()
let watcher=new Watcher()
dep.notify() // Print the results update

summary :

The observer pattern is scheduled by specific targets , For example, when an event triggers ,Dep Will call the observer's method , Therefore, there is a dependency between the subscriber and publisher of the observer .

The publish subscribe mode is called by the unified dispatching center , So publishers and subscribers don't need to know each other's presence .


  1. HTML + CSS + JavaScript to achieve cool Fireworks (cloud like particle text 3D opening)
  2. HTML + CSS + JavaScript realizes 520 advertising love tree (including music), which is necessary for programmers to express themselves
  3. Solve the problem of Web front-end deployment server (it can be deployed online without a server)
  4. HTML + CSS + JS make wedding countdown web page template (520 / Tanabata Valentine's Day / programmer advertisement)
  5. What else can driverless minibus do besides "Park connection"?
  6. Cloud native leads the era of all cloud development
  7. NRM mirror source management tool
  8. Bring it to you, flex Jiugong
  9. Lolstyle UI component development practice (II) -- button group component
  10. Deconstruction assignment in ES6
  11. Luo 2 peerless Tang clan was officially launched. The official gave a key point, and the broadcast time was implied
  12. 20初识前端HTML(1)
  13. 当新零售遇上 Serverless
  14. 20 initial knowledge of front-end HTML (1)
  15. When new retail meets serverless
  16. [golang] - go into go language lesson 5 type conversion
  17. [golang] - go into go language lesson 6 conditional expression
  18. HTML5(八)——SVG 之 path 详解
  19. HTML5 (8) -- detailed explanation of SVG path
  20. 需要开通VIP以后页面内容才能复制怎么办?控制台禁用javascript即可
  21. Web前端|CSS入门教程(超详细的CSS使用讲解,适合前端初学者)
  22. 实践积累 —— 用Vue3简单写一个单行横向滚动组件
  23. Serverless 全能选手,再下一城
  24. What if you need to open a VIP to copy the page content? Just disable JavaScript on the console
  25. Web front end | CSS introductory tutorial (super detailed CSS explanation, suitable for front-end beginners)
  26. Practice accumulation - write a single line horizontal scroll component simply with vue3
  27. Dili Reba is thin again. She looks elegant and high in a strapless hollow skirt, and her "palm waist" is beautiful to a new height
  28. Serverless all-round player, next city
  29. The difference between MySQL semi synchronous replication and lossless semi synchronous replication
  30. Vue表单设计器的终极解决方案
  31. The ultimate solution for Vue form designer
  32. Nginx从理论到实践超详细笔记
  33. Yu Shuxin's red backless swimsuit is split to the waist and tail, with a concave convex figure and excessive color matching, and his face is white to dazzling
  34. Nginx ultra detailed notes from theory to practice
  35. 【动画消消乐|CSS】086.炫酷水波浪Loading过渡动画
  36. typecho全站启用https
  37. CCTV has another popular employee. The off-site interpretation is very professional, and the appearance ability is no less than that of Wang Bingbing
  38. [animation Xiaole | CSS] 086. Cool water wave loading transition animation
  39. Enable HTTPS in Typecho
  40. 50天用JavaScript完成50个web项目,我学到了什么?
  41. 根据JavaScript中原生的XMLHttpRequest实现jQuery的Ajax
  42. What have I learned from completing 50 web projects with JavaScript in 50 days?
  43. "My neighbor doesn't grow up" has hit the whole network. There are countless horse music circles, and actor Zhou Xiaochuan has successfully made a circle
  44. 根据JavaScript中原生的XMLHttpRequest实现jQuery的Ajax
  45. Implement the Ajax of jQuery according to the native XMLHttpRequest in JavaScript
  46. Implement the Ajax of jQuery according to the native XMLHttpRequest in JavaScript
  47. 30 + women still wear less T-shirts and jeans. If they wear them like stars, they will lose weight
  48. 数栈技术分享前端篇:TS,看你哪里逃~
  49. Several stack technology sharing front end: TS, see where you escape~
  50. 舍弃Kong和Nginx,Apache APISIX 在趣链科技 BaaS 平台的落地实践
  51. Abandon the landing practice of Kong and nginx, Apache apisik on the baas platform of fun chain technology
  52. 浪迹天涯king教你用elementui做复杂的表格,去处理报表数据(合并表头,合并表体行和列)
  53. 前端HTML两万字图文大总结,快来看看你会多少!【️熬夜整理&建议收藏️】
  54. Wandering around the world king teaches you to use elementui to make complex tables and process report data (merge header, merge table body rows and columns)
  55. 路由刷新数据丢失 - vuex数据读取的问题
  56. Front end HTML 20000 word graphic summary, come and see how much you can【 Stay up late to sort out & suggestions]
  57. Route refresh data loss - vuex data reading problem
  58. Systemctl系统启动Nginx服务脚本
  59. Systemctl system startup nginx service script
  60. sleepless