013_Vue监听器
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013_Vue监听器
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1. 監(jiān)聽(tīng)器的應(yīng)用場(chǎng)景
1.1. 數(shù)據(jù)變化時(shí)執(zhí)行異步或開(kāi)銷(xiāo)比較大的操作。
1.2. 監(jiān)聽(tīng)器用法?
watch: {// 監(jiān)聽(tīng)firstName的值的變化firstName: function(val){this.fullName = val + "" + this.lastName;} }2. 監(jiān)聽(tīng)器例子
2.1. 代碼?
<!DOCTYPE html> <html><head><meta charset="utf-8" /><title>監(jiān)聽(tīng)器</title></head><body><div id="app"><div><span>姓: </span><input type="text" v-model="firstName" /></div><div><span>名: </span><input type="text" v-model="lastName" /></div><div>{{fullName}}</div><div>{{computedFullName}}</div><hr /><div><span>用戶(hù)名:</span><span><input type="text" v-model.lazy='userName' /></span><span>{{tip}}</span></div></div><script type="text/javascript" src="vue.min.js"></script><script type="text/javascript">var vm = new Vue({el: "#app",data: {firstName: "",lastName: "",fullName: "",userName: "",tip: ""},methods: {checkUserName: function(userName){var me = this;setTimeout(function(){if(userName == "zhangsan"){me.tip = "用戶(hù)名已經(jīng)存在, 請(qǐng)換一個(gè)..."}else{me.tip = "用戶(hù)名可用..."}}, 2000);}},computed: {computedFullName: function(){var value = this.firstName + this.lastName;console.log(value)return value;}},watch: {firstName: function(val){this.fullName = val + "" + this.lastName;},lastName: function(val){this.fullName = this.firstName + val;},userName: function(val){this.checkUserName(val);this.tip = "正在驗(yàn)證...";}}});</script></body> </html>2.2. 效果圖
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