Vue中v-model原理

通过父子组件通信揭开v-model实现原理

父子组件通信

App.vue

<template>
  <p>父组件:{{num}}</p>
  <hello-world :num="num" @change="change"></hello-world>
</template>

<script setup>
import {ref} from "vue";
import HelloWorld from "./components/HelloWorld.vue";

const num = ref(0);
function change(value){
  num.value = value;
}

</script>
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HelloWorld.vue

<template>
  <p>子组件:{{numProps.num}}</p>
  <button @click="add">add</button>
</template>

<script setup>
const numProps = defineProps({
  num:Number
});
const emit = defineEmits("change");
function add(){
  emit('change',numProps.num+1);
}
</script>
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改变变量名称和方法名称

App.vue

<template>
  <p>父组件:{{num}}</p>
  <hello-world :modelValue="num" @update:modelValue="change"></hello-world>
</template>

<script setup>
import {ref} from "vue";
import HelloWorld from "./components/HelloWorld.vue";

const num = ref(0);
function change(value){
  num.value = value;
}

</script>

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HelloWorld.vue

<template>
  <p>子组件:{{numProps.modelValue}}</p>
  <button @click="add">add</button>
</template>

<script setup>
const numProps = defineProps({
  modelValue:Number
});
const emit = defineEmits("update:modelValue");
function add(){
  emit('update:modelValue',numProps.modelValue+1);
}
</script>

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简写向子组件通信

App.vue

<template>
  <p>父组件:{{num}}</p>
  <hello-world v-model:="num"></hello-world>
</template>

<script setup>
import {ref} from "vue";
import HelloWorld from "./components/HelloWorld.vue";
const num = ref(0);
</script>
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简写子组件

HelloWorld.vue

<template>
  <input type="text"
         :value="modelValue"
         @input="(e) => $emit('update:modelValue',e.target.value)"/>
<!--  <input type="text"
         :value="modelValue"
         @input="$emit('update:modelValue',$event.target.value)"/>-->
</template>

<script setup>
defineProps({
  modelValue:Number
});
defineEmits("update:modelValue");

</script>
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