v-model 用于表单控件的双向绑定。实际上就是对html控件的value值进行操作的一个命令
作用于带value的控件，比如input，selected，textarea等。
1、input(text) 、textarea
<body>
<div id="app">
<input type="text" v-model="message" placeholder="edit me">
<p>Message is: {{ message }}</p>
</div>
<script src="vue.js"></script>
<script>
var app = new Vue({
el: '#app',
data: {
message: '',
},
});
</script>
2、input(checkbox) 复选框
<body>
<div id="app">
<p>多个复选框：</p>
<input type="checkbox" id="runoob" value="Runoob" v-model="messages">
<label for="runoob">Runoob</label>
<input type="checkbox" id="google" value="Google" v-model="messages">
<label for="google">Google</label>
<input type="checkbox" id="taobao" value="Taobao" v-model="messages">
<label for="taobao">taobao</label>
<p>checkMessage is: {{ messages }}</p>
</div>
<script src="vue.js"></script>
<script>
var app = new Vue({
el: '#app',
data: {
messages: [],
},
});
</script>
3、input(radio) 单选按钮
<body>
<div id="app">
<input type="radio" id="runoob" value="Runoob" v-model="messages">
<label for="runoob">Runoob</label>
<input type="radio" id="google" value="Google" v-model="messages">
<label for="google">Google</label>
<input type="radio" id="taobao" value="Taobao" v-model="messages">
<label for="taobao">taobao</label>
<p>checkMessage is: {{ messages }}</p>
</div>
<script src="vue.js"></script>
<script>
var app = new Vue({
el: '#app',
data: {
messages: 'Taobao',
},
});
</script>
4、selected 下拉框
<body>
<div id="app">
<select v-model="selected">
<option disabled value="">请选择</option>
<option value ='a'>A</option>
<option value='b'>B</option>
<option value='c'>C</option>
</select>
<span>Selected: {{ selected }}</span>
</div>
<script src="vue.js"></script>
<script>
var app = new Vue({
el: '#app',
data: {
selected: 'a',
},
});
</script>
5、绑定修饰符
<body>
<div id="app">
<input v-model.lazy="msg"> <!-- //从实时触发变成change时同步，即焦点离开此控件时触发 -->
<input v-model.number="age" type="number"> <!-- //将变量转成数字型，如果转换失败，则返回原来的值 -->
<input v-model.trim="msg">
<p> {{msg}}</p>
</div>
<script src="vue.js"></script>
<script>
var app = new Vue({
el: '#app',
data: {
msg: '',
age:1,
},
});
</script>