How to implement asynchronous component loading in vue+webpack?

Below I will share with you a method for implementing asynchronous component loading with vue webpack. It has a good reference value and I hope it will be helpful to everyone.

8.9 update: When I wanted to move to csdn before, I couldn’t transfer the blog because of the invitation code problem, so I went to the blog park. Today I found that csdn had moved the article for me. It is necessary to correct it. This article.

When I wrote this article, I was new to vue, so I was a little confused when tinkering with it.

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It took a long time to do something that was originally very simple.

1. The vue document only gives an example of Vue.component('comp_name', function(resolve,reject){}) loading component definition content via ajax in the callback, but now I am used to writing components in .vue files. , how to do it when clicking on the route to get .vue?

2. Webpack's coding-split supports commonjs/amd syntax, that is, there are different implementations. After checking many messy cases on the Internet, I finally settled on two ways of writing

commonjs syntax: const setting = resolve => require.ensure([], ()=> resolve(require('./components /setting.vue')),'setting');

Document writing method: resolve =>require(['./components/setting.vue')],resolve);//Lazy loading

At that time, I practiced together with routing. The first one I used was what I saw on github. require.ensure is the syntax of webpack. When packaging, the code specified in the require.ensure part is cut out and packaged. On another chunk, just add the chunkFileName item in webpack.config.js. The three parameters of require.ensure are: dependent URL, callback, and custom chunk name.

In fact, the essence of code split is to separate the modules you require and package them separately. When used, the browser initiates asynchronous acquisition and inserts it into the head through scriptdom. This is it The underlying implementation. When I tried it myself, every time I obtained an asynchronous component, two tags were inserted into the head, one script and one yigestyle, because the .vue file will eventually be parsed into html, css and js.

PS: In fact, the sample code on the webpack official website does not have the resolution=> writing method. Just require.ensure directly in the function. I was a little confused at first. I couldn’t find an explanation on the Internet, so I did my own research. Found the require.ensure function. After webpack packaging and compilation,

is a function of _webpack_require_.e, which itself is a thenable instance. The callback of require.ensure is placed in _webpack_require_.e.then (fn), it is immediately obvious that the syntax of webpack itself should be a promise instance, but in the above way of getting the vue component, because require.ensure is an encapsulated syntax, we have to pass resolve into its parent function , obtain and call it through the scope chain in the callback of require.ensure. This also reveals that the resolve function does not have to be in the function parameters of the promise, and its appearance position can be flexibly set. As mentioned in Teacher Ruan Yifeng's ES6 introduction, the resolve function is provided by the js engine and does not need to be deployed by yourself.

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First of all, the use of asynchronous components is not as complicated as you thought when you first came into contact with it.

1. If you apply the official website method:

HTML:

 //点击按钮后，show为真,先获取child组件，再渲染p内容

 
 

JS:

//...
data () {
  return {
   msg: 'Welcome to Your Vue.js App',
   show:false
  }
 },
 methods: {
  showchild:function(){
   this.show=true;
   }
 },
 components: {
   'child': function(resolve) {
    require(['./components/child.vue'], resolve);
 }

*Note: When loading asynchronous components, do not ignore the .vue after the component name.

This example should be more intuitive. After clicking the button, the Boolean value of the variable show is changed to true. Since child.vue is an asynchronous component, the component will be obtained through ajax first and then rendered.

In many cases, asynchronous components will be used with vue-router to switch views. In fact, any syntax can be used at this time.

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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