An article explaining in detail how vue implements v-model (with code examples)

• Why use v-model? As a two-way binding instruction, v-model is also one of the two core functions of vue. It is very convenient to use and improves the efficiency of front-end development. In the view layer, the model layer needs data interaction with each other, so v-model can be used.
• A brief description of the principle of v-model

v-model mainly provides two functions. The input value of the view layer affects the attribute value of the data. If the value of the data attribute changes, the view will be updated. The value of the layer changes.

The core is that on the one hand, the modal layer hijacks each attribute through defineProperty, and once changes are detected, it is updated through the relevant page elements. On the other hand, by compiling the template file, the input event is bound to the v-model of the control, so that the page input can update the relevant data attribute values ​​in real time.

• What is v-model v-model is Vue's two-way binding instruction. It can synchronously update the value input by the control on the page to the relevant bound data attribute. It will also update the value of the input control on the page when the data binding attribute is updated.

vue2.0 implementation method

• Parent component

<template>
  <div id="app">
    {{username}} <br/>
    <my-input type="text" v-model="username"></my-input>
  </div>
</template>

<script>
import myinput from &#39;./components/myinput&#39;
export default {
  name: &#39;App&#39;,
  components:{
      myinput
  },
  data(){
    return {
      username:&#39;&#39;
    }
  }

}
</script>

• myinput.vue：

<template>
    <div class="my-input">
        <input type="text" class="my-input__inner" @input="handleInput"/>
    </div>
</template>

<script>
    export default {
        name: "myinput",
        props:{
            value:{ //获取父组件的数据value
                type:String,
                default:&#39;&#39;
            }
        },
        methods:{
            handleInput(e){
                this.$emit(&#39;input&#39;,e.target.value) //触发父组件的input事件
            }
        }
    }
</script>

The most common thing is to control the display and closing of the modal box. We can also use v-model to take the el-dialog component of element as an example

• App.vue

<template>
    <div>
        <kmDialog
            v-model="showDialog"
        >
        <el-button @click="show">点我</el-button>
    </div>
</template>
<script>
    import kmDialog from &#39;KmDialog.vue&#39;
    export default {
        components: {
            KmDialog
        }
        data () {
            return {
                showDialog: false
            }
        },
        methods: {
            show() {
                this.showDialog = true
            }
        }
    }
</script>

• KmDialog.vue

<template>
    <el-dialog
        :title="isEdit ? &#39;编辑设备&#39; : &#39;新增设备&#39;"
        :visible.sync="value"
        width="40%"
        @close="cancel"
      >
        <span>这是一段信息</span>
    </el-dialog>
</template>
<script>
    export default {
        props: {
            value: {
                default: false,
                type: Boolean
            }
        },
        methods: {
            cancel() {
                this.$emit(&#39;input&#39;, false)
            }
        }
    }
</script>

Recommended learning: "vue.js Video Tutorial"