<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>4.天气案例_监视简写</title>
<script type="text/javascript" src="../vue.js"></script>
</head>
<body>
<div id="root">
<h3>今天天气很{{showInfo}}</h3>
<button @click="changeWeather">切换天气</button>
</div>
<script>
Vue.config.productionTip = false
const vm = new Vue({
el: "#root",
data: {
'isHot': true,
},
computed: {
showInfo() {
return this.isHot ? '炎热' : '凉爽'
}
},
methods: {
changeWeather() {
this.isHot = !this.isHot
}
},
watch: {
// // 完整写法
// isHot: {
// immediate: true,
// deep: true,
// handler(newValue, oldValue) {
// console.log('isHot 被修改', newValue, oldValue)
// }
// } ,
// // 简写写法
// isHot(newValue, oldValue) {
// console.log('isHot 被修改', newValue, oldValue)
// }
}
})
// 外置完整写法
// vm.$watch('isHot', {
// immediate: true,
// deep: true,
// handler(newValue, oldValue) {
// console.log('isHot 被修改', newValue, oldValue)
// }
// })
// 外置简写写法
vm.$watch('isHot', function(newValue, oldValue){
console.log('isHot 被修改', newValue, oldValue)
})
</script>
</body>
</html>