报错：Avoid mutating a prop directly since the value will be overwritten whenever the parent component........
原因：所有的 prop 都使得其父子 prop 之间形成了一个单向下行绑定：父级 prop 的更新会向下流动到子组件中，但是反过来则不行。（父组件更新，子组件中的prop值也会更新，但子组件不能修改由父组件传递过来的值）
不能直接对父组件传来的值进行双向绑定，要先子组件里定义新的变量来接收父组件传来的值，接着我们可以使用v-modal+watch属性 或者 使用:binfd="" + @input=" func"(再定义这个func通过传入的event 得到改变的值，将event.target.value赋值给新变量)
1 <!DOCTYPE html>
2 <html lang="en">
3 <head>
4 <meta charset="UTF-8">
5 <meta name="viewport" content="width=device-width, initial-scale=1.0">
6 <meta http-equiv="X-UA-Compatible" content="ie=edge">
7 <title>Document</title>
8 </head>
9 <body>
10
11 <div id="app">
12 <h3>我是父组件</h3>
13 <templ :num-from-father="fatherData"
14 :num-from-father2="fatherData2"
15 @change1="changeFunc1"
16 @change2="changeFunc2"/>
17 </div>
18
19 <template id="temp">
20 <div>
21 <h3>我是子组件</h3>
22 <p>props1:{{numFromFather}}</p>
23 <p>转存的值:{{receiveNum1}}</p>
24 <!-- 方法1 -->
25 <input type="number" :bind="receiveNum1" @input="receiveNum1Input">
26 <p>props2:{{numFromFather2}}</p>
27 <p>转存的值:{{receiveNum2}}</p>
28 <!-- 方法2 使用watch -->
29 <input type="number" v-model="receiveNum2">
30 </div>
31 </template>
32 <script src="/js/vue.js"></script>
33 <script>
34 const vm = new Vue({
35 el:'#app',
36 data:{
37 fatherData:0,
38 fatherData2:10
39 },
40 methods: {
41 changeFunc1(value){
42 this.fatherData = value*1;
43 },
44 changeFunc2(value){
45 this.fatherData2 = value*1;
46 }
47 },
48 components:{
49 templ:{
50 template:'#temp',
51 props:{
52 numFromFather:Number,
53 numFromFather2:Number,
54 },
55 data(){
56 return{
57 receiveNum1:this.numFromFather,
58 receiveNum2:this.numFromFather2,
59 }
60 },
61 methods: {
62 receiveNum1Input(event){
63 this.receiveNum1 = event.target.value;
64 this.$emit('change1',this.receiveNum1);
65 this.receiveNum2 = this.receiveNum1*100;
66 this.$emit('change2',this.receiveNum2);
67 }
68 },
69 watch: {
70 receiveNum2(newValue){
71 this.receiveNum2 = newValue;
72 this.$emit('change2',this.receiveNum2);
73 this.receiveNum1 = this.receiveNum2/100;
74 this.$emit('change1',this.receiveNum1);
75 }
76 },
77 }
78 }
79 })
80 </script>
81 </body>
82 </html>