watch和computed
阿新 • • 發佈:2018-11-30
-watch可以單個監聽
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="UTF-8"> <title>Title</title> <meta name="viewport" content="width=device-width, initial-scale=1"> </head> <body> <div id="app"> <p>{{ msg }}</p> <button @click = 'clickHandler'>修改</button> </div> <script src="vue.js"></script> <script> newwatch單個監聽的例項Vue({ el:'#app', data(){ return { msg:"alex", age:18 } }, methods:{ clickHandler(){ this.msg = "wusir" } }, watch:{//watch單個屬性,如果想監聽多個屬性 宣告多個屬性的監聽 'msg':function (value) { console.log(value); if (value === 'wusir'){ alert(1); this.msg = '大武sir' } },'age' :function (value) { } } }) </script> </body> </html>
-計算屬性computed監聽多個屬性
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="UTF-8"> <title>Title</title> <meta name="viewport" content="width=device-width, initial-scale=1"> </head> <body> <div id="app"> <p>{{ myMsg }}</p> <button @click='clickHandler'>修改</button> </div> <script src="vue.js"></script> <script> let vm = new Vue({ el: '#app', data() { return { msg: "alex", age: 18 } }, created() { //定時器 ajax 庫 function(){} setInterval(() => { }) }, methods: { clickHandler() { //this的指向就是當前物件 this.msg = "wusir"; this.age = 20; }, clickHandler: function () { console.log(this); } }, computed: { myMsg: function () { //業務邏輯 // 計算屬性預設只有getter方法 return `我的名字叫${this.msg},年齡是${this.age}`; } } }) console.log(vm); </script> </body> </html>computed