更改从子组件内的 props 创建的数组的元素也会影响父组件的 props |浏览器 3

Question

我有一个父组件 (App)，其中有一个对象数组。我将这个数组作为道具传递给子组件（UserLocations）。现在在子组件中，我使用这个数组并创建一个数据变量。

所以如果我要更改数组的一个元素，那么为什么父组件的属性也会更改。

App.Vue

<template>
  <user-locations :initalLocations="locations"/>
</template>

<script>
import UserLocations from './components/UserLocations.vue'

export default {
  name: 'App',
  components: {
    UserLocations
  },
  mounted() {
  },
  data: function() {
    return {
      locations: [
        {"id": 121, name: "test 121", "order": 1},
        {"id": 122, name: "test 122", "order": 2},
        {"id": 123, name: "test 123", "order": 3},
        {"id": 124, name: "test 124", "order": 4}
      ]
    }
  }
}
</script>

UserLocations.vue

<template>
    <ul>
        <li v-for="(location) in locations"
        :key="location.id"
        > 
        <span @click="decreaseOrder(location)">Up</span>
        {{ location.name}} {{location.order}}
        <span @click="increaseOrder(location)">down</span>
        </li>
    </ul>
</template>
<script>

export default {
    data: function() {
        return {
            locations: [...this.initalLocations]
        }
    },
    props: {
        initalLocations: { 
            type: Array,
        },
    },
    // computed: {
    //     locations() {
    //         return [
    //             ...this.initalLocations
    //         ]
    //     }
    // },
    methods:{
        increaseOrder(location) {
            if (location.order != this.locations.length) {
                this.locations = this.locations.map(l => {
                    var returnLocation = {...l};
                    if (l.id == location.id) {
                        l.order += 1
                    }
                    return returnLocation
                });
            }
        },
        decreaseOrder(location) {
            if (location.order != 1) {
                this.locations = this.locations.map(l => {
                    var returnLocation = {...l};
                    if (l.id == location.id) {
                        l.order -= 1
                    }
                    return returnLocation
                });
            }
        },
    }
}
</script>

如您所见，我使用 initalLocations 道具在 UserLocations 组件内制作位置道具，当我通过单击 up/down 按钮更改数组的一个对象时，它会更改传递给 UserLocations 的道具而不是更改本地数据“位置”

Answer 1

扩展运算符不能深入地克隆数组，您需要一个克隆数组而不是引用它的函数：

<script>
function deepCopy(obj) {
    if (typeof obj !== 'object' || obj === null) {
        return obj;
    }


    if (obj instanceof Array) {
        return obj.reduce((arr, item, i) => {
            arr[i] = deepCopy(item);
            return arr;
        }, []);
    }

    if (obj instanceof Object) {
        return Object.keys(obj).reduce((newObj, key) => {
            newObj[key] = deepCopy(obj[key]);
            return newObj;
        }, {})
    }
}

export default {
    data: function() {
        return {
            locations: deepCopy(this.initalLocations)
        }
    },
...

更改从子组件内的 props 创建的数组的元素也会影响父组件的 props |浏览器 3

Changing the element of an array created from the props inside the child component also affect the parent component's props | Vuejs 3

javascript

arrays

spread

vue.js