相反，根据道具的值使用数据或计算属性.VueJS

问题描述

好吧，我正在尝试更改 Vue 中变量"的值，但是当我单击按钮时，它们会在控制台中抛出一条消息:

Well, I'm trying to change a value of "variable" in Vue, but when I click on the button they throw a message in console:

[Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or computed property based on the prop's value. Prop being mutated: "menuOpen"

我不知道如何解决这个问题...

I have no idea how to solve this problem...

我的文件.vue:

<template>
  <button v-on:click="changeValue()">ALTERAR</button>
</template>

<script>

export default {
  name: 'layout',
  props: [ 'menuOpen' ],
  methods: {
    changeValue: function () {
      this.menuOpen = !this.menuOpen
    }
  },
}

</script>

谁能帮帮我?谢谢

推荐答案

警告很清楚.在您的 changeValue 方法中，您正在更改属性的值，menuOpen.这将更改组件内部的值，但是如果 父 组件因任何原因必须重新渲染，那么无论内部 组件的值是什么，组件都将被覆盖组件外部的当前状态.

The warning is pretty clear. In your changeValue method you are changing the value of the property, menuOpen. This will change the value internally to the component, but if the parent component has to re-render for any reason, then whatever the value is inside the component will be overwritten with the current state outside the component.

通常情况下，您通过复制值供内部使用来处理此问题.

Typically you handle this by making a copy of the value for internal use.

export default {
  name: 'layout',
  props: [ 'menuOpen' ],
  data(){
      return {
          isOpen: this.menuOpen
      }
  },
  methods: {
    changeValue: function () {
      this.isOpen= !this.isOpen
    }
  },
}

如果您需要将值的更改传达回父级，那么您应该$emit 更改.

If you need to communicate the change of the value back to the parent, then you should $emit the change.

changeValue: function () {
    this.isOpen= !this.isOpen
    this.$emit('menu-open', this.isOpen)
}

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