<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script src="./lib/vue-2.4.0.js"></script>
</head>
<body>
<div id="app">
<!-- 分析： -->
<!-- 1. 我們要監聽到 文本框數據的改變，這樣才能知道 什么時候去拼接 出一個 fullname -->
<!-- 2. 如何監聽到 文本框的數據改變呢？？？ -->
<input type="text" v-model="firstname" @keyup="getFullname"> +
<input type="text" v-model="lastname" @keyup="getFullname"> =
<input type="text" v-model="fullname">
</div>
<script>
// 創建 Vue 實例，得到 ViewModel
var vm = new Vue({
el: '#app',
data: {
firstname: '',
lastname: '',
fullname: ''
},
methods: {
getFullname() {
this.fullname = this.firstname + '-' + this.lastname
}
}
});
</script>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script src="./lib/vue-2.4.0.js"></script>
</head>
<body>
<div id="app">
<input type="text" v-model="firstname"> +
<input type="text" v-model="lastname"> =
<input type="text" v-model="fullname">
</div>
<script>
// 創建 Vue 實例，得到 ViewModel
var vm = new Vue({
el: '#app',
data: {
firstname: '',
lastname: '',
fullname: ''
},
methods: {},
watch: { // 使用這個 屬性，可以監視 data 中指定數據的變化，然后觸發這個 watch 中對應的 function 處理函數
'firstname': function (newVal, oldVal) {
// console.log('監視到了 firstname 的變化')
// this.fullname = this.firstname + '-' + this.lastname
// console.log(newVal + ' --- ' + oldVal)
this.fullname = newVal + '-' + this.lastname
},
'lastname': function (newVal) {
this.fullname = this.firstname + '-' + newVal
}
}
});
</script>
</body>
</html>
