事件回傳之 $listeners
組件由下向上回傳事件
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="Generator" content="EditPlus®">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<title>vue測試</title>
<script src="https://cdn.jsdelivr.net/npm/vue@2.5.22/dist/vue.js"></script>
<style>
</style>
</head>
<body>
<div id="app">
<base-input
v-model="username"
label="基礎輸入組件"
@click.native="handleBaseInputClick"
v-on:focus="handleBaseInputFocus"
placeholder="請輸入您的名字"
class="username-input"/>
</div>
<script>
// 注冊組件
// 因為base-input的外層是一個label元素，所以默認情況下使用v-on:focus是無效的，所以需要配合$listeners使用，該屬性可以把事件的監聽指向組件中某個特定的元素
// 注意：如果父級的事件添加了.native修飾符，在$listeners中不會體現出來的
Vue.component('base-input',{
inheritAttrs: false,
props: ['label','value'],
template: `
<label id="base-label">
{{label}}
<input v-bind:value="value" v-bind="$attrs" v-on="inputListeners"/>
</label>
`,
data: function() {
return {
}
},
computed: {
inputListeners () {
var vm = this
return Object.assign({},
this.$listeners,
{
input: function () {
vm.$emit('input', event.target.value)
},
focus: function (event) {
vm.$emit('focus', '哈哈哈，onfocus了')
}
}
)
}
},
mounted: function(){
console.log(`$attrs:`)
console.log(this.$attrs)
console.log(`$listeners:`)
console.log(this.$listeners) // 父級添加的所有屬性都在這里
},
methods: {
}
})
var vm = new Vue({
el: '#app',
data: {
username: ''
},
created: function(){
},
beforeUpdate: function(){
},
computed: {
},
beforeUpdate: function () {
console.log(this.username)
},
methods: {
handleBaseInputFocus: function(ev){
console.log(ev)
},
handleBaseInputClick: function(ev){
console.log(ev.type)
}
}
})
</script>
</body>
</html>
-----------------------------------------------------------
實例二
<div id="app"> <child1 :p-child1="child1" :p-child2="child2" :p-child-attrs="1231" v-on:test1="onTest1" v-on:test2="onTest2"> </child1> </div> <script> Vue.component("Child1", { inheritAttrs: true, props: ["pChild1"], template: ` <div class="child-1"> <p>in child1:</p> <p>props: {{pChild1}}</p> <p>$attrs: {{this.$attrs}}</p> <hr> <child2 v-bind="$attrs" v-on="$listeners"></child2></div>`, mounted: function() { this.$emit("test1"); } }); Vue.component("Child2", { inheritAttrs: true, props: ["pChild2"], template: ` <div class="child-2"> <p>in child->child2:</p> <p>props: {{pChild2}}</p> <p>$attrs: {{this.$attrs}}</p> <button @click="$emit('test2','按鈕點擊')">觸發事件</button> <hr> </div>`, mounted: function() { this.$emit("test2"); } }); const app = new Vue({ el: "#app", data: { child1: "pChild1的值", child2: "pChild2的值" }, methods: { onTest1() { console.log("test1 running..."); }, onTest2(value) { console.log("test2 running..." + value); } }