<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="app">
        <span>请选择语言，已选择{{selected.length}}种</span>
        <br>
        <select name="s1" id="s1" multiple v-model="selected">
            <option v-for="op in languages" v-bind:value="op.value">
                {{op.text}}
            </option>
        </select>
    </div>

    <script src="../js/vue.js"></script>

    <script>
        let vm = new Vue({
            el:'#app',
            data:{
                selected:[],
                languages:[
                    {
                        text:'python',
                        value:101
                    },
                    {
                        text:'javascript',
                        value:102
                    },
                    {
                        text:'pascal',
                        value:103
                    }
                ]
            }
        });
    </script>
</body>
</html>