-watch可以单个监听
<!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>
new Vue({
el:'#app',
data(){
return {
msg:"alex",
age:18
}
},
methods:{
clickHandler(){
this.msg = "wusir"
}
},
watch:{
//watch单个属性，如果想监听多个属性 声明多个属性的监听
'msg':function (value) {
console.log(value);
if (value === 'wusir'){
alert(1);
this.msg = '大武sir'
}
},
'age' :function (value) {
}
}
})
</script>
</body>
</html>
-计算属性computed监听多个属性
<!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() {
//定时器 ajax 库 function(){}
setInterval(() => {
})
},
methods: {
clickHandler() {
//this的指向就是当前对象
this.msg = "wusir";
this.age = 20;
},
clickHandler: function () {
console.log(this);
}
},
computed: {
myMsg: function () {
//业务逻辑
// 计算属性默认只有getter方法
return `我的名字叫${this.msg},年龄是${this.age}`;
}
}
})
console.log(vm);
</script>
</body>
</html>