webveuje/vue/表单输入绑定v-model.md
2020-12-23 10:29:16 +08:00

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# 表单输入绑定 v-model
### 基本用法
用v-model 指令在表单input, textarea, select 元素上创建双向绑定值
v-model 使用时会忽略所有表单元素的value, checked, selected 属性设置的初始值表单元素的初始值由v-model的初始值决定
v-model为不同的输入元素使用不同的property并抛出不同的事件
- text 和 textarea 元素使用 `value` property 和 `input` 事件;
- checkbox 和 radio 使用 `checked` property 和 `change` 事件;
- select 字段将 `value` 作为 prop 并将 `change` 作为事件。
### v-model 使用
语法v-model="data中的属性"
示例:
- 文本
```
<input v-model="message" placeholder="edit me">
<p>Message is: {{ message }}</p>
```
- 多行文本
```
<span>Multiline message is:</span>
<p style="white-space: pre-line;">{{ message }}</p>
<br>
<textarea v-model="message" placeholder="add multiple lines"></textarea>
```
- 复选框
- 单个复选框
```
<input type="checkbox" id="checkbox" v-model="checked">
<label for="checkbox">{{ checked }}</label>
```
![image-20201222175835286](表单输入绑定v-model.assets/image-20201222175835286.png)未选中
![image-20201222175902811](表单输入绑定v-model.assets/image-20201222175902811.png) 已选中
- 多个复选框 绑定到同一个数组
```
<input type="checkbox" id="jack" value="Jackval" v-model="checkedNames">
<label for="jack">Jack</label>
<input type="checkbox" id="john" value="Johnval" v-model="checkedNames">
<label for="john">John</label>
<input type="checkbox" id="mike" value="Mikeval" v-model="checkedNames">
<label for="mike">Mike</label>
<br>
<span>Checked names: {{ checkedNames }}</span>
```
```
new Vue({
el: '...',
data: {
checkedNames: []
}
})
```
未选择时:![image-20201222180149362](表单输入绑定v-model.assets/image-20201222180149362.png)
选中时:![image-20201222180209565](表单输入绑定v-model.assets/image-20201222180209565.png)
> 注 选中的时候v-modal对应的是input元素的value 属性
- 单选按钮
```
<div id="example-4">
<input type="radio" id="one" value="Oneval" v-model="picked">
<label for="one">One</label>
<br>
<input type="radio" id="two" value="Twoval" v-model="picked">
<label for="two">Two</label>
<br>
<span>Picked: {{ picked }}</span>
</div>
```
```
new Vue({
el: '#example-4',
data: {
picked: ''
}
})
```
未选时:![image-20201222180600963](表单输入绑定v-model.assets/image-20201222180600963.png)
选择后:
![image-20201222180642082](表单输入绑定v-model.assets/image-20201222180642082.png)
> 注 选中的时候v-modal对应的是input元素的value 属性
- 选择框
- 单选:
```
<div id="example-5">
<select v-model="selected">
<option disabled value="">请选择</option>
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<span>Selected: {{ selected }}</span>
</div>
```
```
new Vue({
el: '...',
data: {
selected: ''
}
})
```
未选择:![image-20201222180952802](表单输入绑定v-model.assets/image-20201222180952802.png)
选择后:![image-20201222181015791](表单输入绑定v-model.assets/image-20201222181015791.png)
> 注 选中的时候v-modal对应的是option元素的value属性
- 多选
```
<div id="example-6">
<select v-model="selected" multiple style="width: 50px;">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<br>
<span>Selected: {{ selected }}</span>
</div>
```
```
new Vue({
el: '#example-6',
data: {
selected: []
}
})
```