vue3 表单输入绑定

一、基础

 v-model 指令在表单 <input>、<textarea> 及 <select> 元素上创建双向数据绑定

1.文本

    <div id="vm">
        <input v-model="message" placeholder="edit me" />
        <p>Message is: {{ message }}</p>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    message:null
                }
            }
        }).mount('#vm')
    </script>

2.多行文本

        <p style="white-space: pre-line;">{{ message }}</p>
        <br>
        <textarea v-model="message" ></textarea>

文本区域插值不起作用，应该使用 v-model 来代替

3.复选框

    <div id="vm">
        <input type="checkbox" id="jack" value="Jack" v-model="checkedNames">
        <label for="jack">Jack</label>
        <input type="checkbox" id="john" value="John" v-model="checkedNames">
        <label for="john">John</label>
        <input type="checkbox" id="mike" value="Mike" v-model="checkedNames">
        <label for="mike">Mike</label>
        <br>
        <span>Checked names: {{ checkedNames }}</span>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    checkedNames: []
                }
            }
        }).mount('#vm')
    </script>

4.单选按钮

    <div id="vm">
        <input type="radio" id="one" value="One" v-model="picked">
        <label for="one">One</label>
        <br>
        <input type="radio" id="two" value="Two" v-model="picked">
        <label for="two">Two</label>
        <br>
        <span>Picked: {{ picked }}</span>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    picked: ''
                }
            }
        }).mount('#vm')
    </script>

5.选择框

（1）简单

   <div id="vm">
        <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>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    selected: ''
                }
            }
        }).mount('#vm')
    </script>

（2）多选

    <div id="vm">
        <select v-model="selected" multiple style=" 50px;">
            <option>A</option>
            <option>B</option>
            <option>C</option>
        </select>
        <br>
        <span>Selected: {{ selected }}</span>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    selected: []
                }
            }
        }).mount('#vm')
    </script>

（3）v-for动态渲染

    <div id="vm">
        <select v-model="selected">
            <option v-for="option in options" v-bind:value="option.value">
                {{ option.text }}
            </option>
        </select>
        <span>Selected: {{ selected }}</span>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    selected: 'A',
                    options: [
                        { text: 'One', value: 'A' },
                        { text: 'Two', value: 'B' },
                        { text: 'Three', value: 'C' }
                    ]
                }
            }
        }).mount('#vm')
    </script>

二、值绑定

1.复选框

    <div id="vm">
        <input type="checkbox" v-model="toggle" true-value="ok" false-value="no" />
        {{toggle}}
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    toggle:null
                }
            }
        }).mount('#vm')
    </script>

 

2.单选框

    <div id="vm">
        <input type="radio" id="one" v-model="pick" v-bind:value="a" />
        <br>
        <input type="radio" id="two" v-model="pick" v-bind:value="b" />
        <br>
        {{pick}}
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    a: 'aaa',
                    b: 'bbb',
                    pick: null
                }
            }
        }).mount('#vm')
    </script>

 3.下拉框

    <div id="vm">
        <select v-model="selected">
            <!-- 内联对象字面量 -->
            <option :value="{ number: 123 }">123</option>
            <option :value="{ number: 456 }">456</option>
        </select>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return{
                    selected:null
                }
            }
        }).mount('#vm')
    </script>

 

三、修饰符

 1.number

在 type="number" 时，HTML 输入元素的值也总会返回字符串

    <div id="vm">
        <input v-model="age" type="number" >
        {{c}}
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    age:null
                }
            },
            computed:{
                c(){
                    return typeof this.age
                }
            }
        }).mount('#vm')
    </script>

 如果想自动将用户的输入值转为数值类型，可以给 v-model 添加 number 修饰符

    <div id="vm">
        <input v-model.number="age" type="number">
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    age: null
                }
            },
            watch: {
                age(newvalue) {
                   console.log(typeof newvalue)
                }
            }
        }).mount('#vm')
    </script>

2.trim

过滤输入空格

  <div id="vm">
        <input v-model.trim="msg">
        <p>{{msg}}</p>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    msg: ''
                }
            }
        }).mount('#vm')
    </script>

3.lazy

当失去焦点时更新

    <div id="vm">
        <input type="text" v-model.lazy="content">
        <p>{{content}}</p>
    </div>
    <script>
        const v = Vue.createApp({
            data() {
                return {
                    content: ''
                }
            }
        }).mount('#vm')
    </script>