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What is vue.js mixin?

青灯夜游Original: 2020-11-23 11:01:301666browse

Mixing in vue.js is a method or calculated property that distributes reusable functions in Vue components. Purpose: 1. After the constructor has been written, you need to add methods or temporary activities When using the method, mixing in will reduce the pollution of the source code; 2. When using public methods, using the mixing method can reduce the amount of code and achieve code reuse.

This method is suitable for all brands of computers.

Mixins define a portion of reusable methods or computed properties. Mixins can contain arbitrary component options. When a component uses a mixin object, all options of the mixin object will be mixed into the options of the component itself.

Mixins generally have two uses:

1. After you have written the constructor, you need to add methods or methods for temporary activities. This Using mixins from time to time will reduce source code pollution.

2. Public methods are used in many places. Using the mixing method can reduce the amount of code and achieve code reuse.

Basic usage of Mixins

We now have a program that clicks to increment a number. Assuming it has been completed, we hope that every time the data changes A prompt can be printed on the console: "Data has changed".

Code implementation process:

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <script type="text/javascript" src="../assets/js/vue.js"></script>
  <title>Mixins Option Demo</title>
</head>
<body>
  <h1>Mixins Option Demo</h1>
  <hr>
  <div id="app">
    <p>num:{{ num }}</p>
    <P><button @click="add">增加数量</button></P>
  </div>
 
  <script type="text/javascript">
    //额外临时加入时，用于显示日志
    var addLog={
      updated:function(){
        console.log("数据放生变化,变化成"+this.num+".");
      }
    }
    var app=new Vue({
      el:&#39;#app&#39;,
      data:{
        num:1
      },
      methods:{
        add:function(){
          this.num++;
        }
      },
      mixins:[addLog]//混入
    })
  </script>
</body>
</html>

The calling sequence of mixins

In terms of the order of execution, the mixed ones are executed first, and then those in the constructor. It should be noted that this is not an override of the method, but is executed on both sides.

In the constructor of the above code, we also added the updated hook function:

updated:function(){
   console.log("构造器里的updated方法。")
},

At this time, the order of console output is:

mixins data Release the change and change it to the updated method in the 2.
constructor.

PS: When the mixed method and the constructor method have the same name, the mixed method cannot be displayed, that is, it does not work.

Global API mix-in method

We can also define a global mix-in, so that you can have this function by directly introducing js where this code is needed. . Let's take a look at the global mixing method:

Vue.mixin({
  updated:function(){
    console.log(&#39;我是全局被混入的&#39;);
  }
})

PS: The execution order of global mixing is before the methods in the mix and constructor.

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