Element-ui 下拉列表全選多選時 select全選新增一個選擇全部的選項

時間 2019-11-13

標籤 element 下拉列表全選 select 新增一個選擇全部選項简体版

原文原文鏈接

項目裏常常會用到，在一個多選下拉框裏新增一個選擇全部的選項，例如:css

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.5.16/dist/vue.js"></script>
    <link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css">
    <script src="https://unpkg.com/element-ui/lib/index.js"></script>
</head>
<body>
    <div id="app">
        <el-form>
            <el-form-item>
                <el-select  placeholder="請選擇活動區域" multiple v-model="citys">
                      <el-option v-for="item in cities" :label="item.label" :value="item.value" :key="item.value"></el-option>
                </el-select>
              </el-form-item>
          </el-form>
    </div>
    <script>
        new Vue({
            el:"#app",
            data:{
                cities: [
                    {value: 'Beijing',label: '北京'}, 
                    {value: 'Shanghai',label: '上海'}, 
                    {value: 'Nanjing',label: '南京'}, 
                    {value: 'Chengdu',label: '成都'}, 
                    {value: 'Shenzhen',label: '深圳'}, 
                    {value: 'Guangzhou',label: '廣州'}
                ],
                citys:[]
            }
        })
    </script>
</body>
</html>

渲染以下:html

此時能夠多選，若是想要選擇全部選項時，得一個個去點擊，這樣不是很方便，咱們能夠在下拉框裏新增一個選擇全部的選項，經過watch用幾行代碼就能夠實現與其它選項的互斥來實現一鍵多選，以下:vue

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.5.16/dist/vue.js"></script>
    <link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css">
    <script src="https://unpkg.com/element-ui/lib/index.js"></script>
</head>
<body>
    <div id="app">
        <el-form>
            <el-form-item>
                <el-select  placeholder="請選擇活動區域" multiple v-model="citys">
                    <el-option label="選擇全部" value="all"></el-option>
                      <el-option v-for="item in cities" :label="item.label" :value="item.value" :key="item.value"></el-option>
                </el-select>
              </el-form-item>
          </el-form>
    </div>
    <script>
        new Vue({
            el:"#app",
            data:{
                cities: [
                    {value: 'Beijing',label: '北京'}, 
                    {value: 'Shanghai',label: '上海'}, 
                    {value: 'Nanjing',label: '南京'}, 
                    {value: 'Chengdu',label: '成都'}, 
                    {value: 'Shenzhen',label: '深圳'}, 
                    {value: 'Guangzhou',label: '廣州'}
                ],
                citys:[]
            },
            watch:{
                citys:function(val,oldval){
                    if(val.indexOf('all')!=-1 && oldval.indexOf('all')==-1 && val.length>1){                      //若是新的選擇裏有勾選了選擇全部選擇全部 則 只直線勾選全部整個選項
                        this.citys=['all'];
                    }else if(index = val.indexOf('all')!=-1 && oldval.indexOf('all')!=-1 && val.length>1){        //若是操做前有勾選了選擇全部且當前也選中了勾選全部且勾選數量大於1  則移除掉勾選全部
                        this.citys.splice(val.indexOf('all'),1)
                    }
                }
            }
        })
    </script>
</body>
</html>