v-bind 的值在数据更改时不会更改。 Vue.js

Question

我有一个函数 changeActive 可以改变 active 布尔值。但即使活动值发生变化（我使用 console.log 检查），新值也不会在 v-bind 中传递：'active' 到子组件。

<template>
<div style="width:300px; margin: auto;">
      <RatingLabel 
      :rating='rating[0]'
      :active='active'
      style="margin: auto;"
      />
      <RatingLabel 
      :rating='rating[1]'
      style="float: right;"
      />
      <RatingLabel 
      :rating='rating[2]'
      />
      <RatingLabel 
      :rating='rating[3]'
      style="margin: auto;"
      />
</div>
</template>

<script>
import RatingLabel from '../atomic/RatingLabel'
import { mapState } from 'vuex'
export default {
      components: {
            RatingLabel,
      },

      data() {
            return {
                  active: false,
            }
      },

      methods: {
            changeActive() {
                  setTimeout(function(){ 
                        this.active = !this.active;
                        console.log(this.active)
                   }, 3000);
            }
      },

      mounted() {
            this.changeActive()
      },

      computed: mapState(['rating'])
}
</script>

Answer 1

this在回调函数中未定义，必须在调用setTimeout之前将其赋值给全局变量vm，然后在回调函数中使用它：

    changeActive() {
                 let vm=this;
                  setTimeout(function(){ 
                        vm.active = !vm.active;
                        console.log(vm.active)
                   }, 3000);
            }

Answer 2

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

function(){} -> () => {},因为可以访问this

           changeActive() {
                  setTimeout(() => { 
                        this.active = !this.active;
                        console.log(this.active)
                   }, 3000);