本节知识点
app.$watch(" xxx",function(newVal,oldVal){})
代码如下
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<script type="text/javascript" src="js/vue.js"></script>
<title>Watch option</title>
</head>
<body>
<h1>Watch option</h1>
<hr>
<div id="app">
<p>今日温度：{{temperature}}°C</p>
<p>穿衣建议:{{this.suggestion}}</p>
<p>
<button @click="add">添加温度</button>
<button @click="reduce">减少温度</button>
</p>
</div>
<script type="text/javascript">
var suggestion=['T恤短袖','夹克长裙','棉衣羽绒服'];
var app=new Vue({
el:'#app',
data:{
temperature:14,
suggestion:'夹克长裙'
},
methods:{
add:function(){
this.temperature+=5;
},
reduce:function(){
this.temperature-=5;
}
},
// watch:{
// temperature:function(newVal,oldVal){
// if(newVal>=26){
// this.suggestion=suggestion[0];
// }else if(newVal<26 && newVal >=0)
// {
// this.suggestion=suggestion[1];
// }else{
// this.suggestion=suggestion[2];
// }
// }
// }
})
app.$watch('temperature',function(newVal,oldVal){
if(newVal>=26){
this.suggestion=suggestion[0];
}else if(newVal<26 && newVal >=0)
{
this.suggestion=suggestion[1];
}else{
this.suggestion=suggestion[2];
}
})
</script>
</body>
</html>
