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In vue, "$emit" is used to trigger events on the current instance, and nearby parameters will be passed to the listener callback; subcomponents can use "$emit" to trigger custom events of the parent component, and the syntax is: "vm.$emit( event, [...args] )".
The operating environment of this article: Windows 10 system, Vue version 2.9.6, DELL G3 computer.
Use $emit(eventName) in vue to trigger events
$emit(eventName) triggers events on the current instance, with additional parameters will be passed to the listener callback.
Use $emit(eventName) to trigger events
Explanation in Api:
vm.$emit( event, […args] )
Usage of $emit in vue
1. The parent component can Use props to pass data to child components.
2. Subcomponents can use $emit to trigger custom events of parent components.
vm.$emit( event, arg ) //触发当前实例上的事件 vm.$on( event, fn );//监听event事件后运行 fn;
Examples are as follows:
Child component
<template> <div class="train-city"> <h3>父组件传给子组件的toCity:{{sendData}}</h3> <br/><button @click='select(`大连`)'>点击此处将‘大连’发射给父组件</button> </div> </template> <script> export default { name:'trainCity', props:['sendData'], // 用来接收父组件传给子组件的数据 methods:{ select(val) { let data = { cityname: val }; this.$emit('showCityName',data);//select事件触发后,自动触发showCityName事件 } } } </script>
Parent component:
<template> <div>父组件的toCity{{toCity}}</div> <train-city @showCityName="updateCity" :sendData="toCity"></train-city> <template> <script> import TrainCity from "./train-city"; export default { name:'index', components: {TrainCity}, data () { return { toCity:"北京" } }, methods:{ updateCity(data){//触发子组件城市选择-选择城市的事件 this.toCity = data.cityname;//改变了父组件的值 console.log('toCity:'+this.toCity) } } } </script>
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