a)         遍历数组，参数(item,index) in list

b)        遍历对象，参数(value,key,index) in list

c)         遍历数字，num in 10 (1~10)

d)        key在使用v-for的时候都需要去设置key

                                i.              让界面元素和数组里的每个记录进行绑定

                              ii.              key只能是字符串或者数字

                             iii.              key必须是唯一的

示例：

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="lib/jquery/jquery-3.4.1.min.js"></script>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
</head>

<body>
    <div id='app'>
        <!-- 遍历数组 -->
        <ul>
            <li v-for="(item,index) in list">{{index}}{{item}}</li>
        </ul>
        <!-- 遍历对象 -->
        <ul>
            <li v-for="(value,key,index) in person">
                {{value}}
                {{key}}
                {{index}}
            </li>
        </ul>
        <!-- 遍历数组对象 -->
        <ul>
            <li v-for="(item2,index2) in courseList">
                {{item2.courseTitle}}
            </li>
        </ul>
        <!-- 遍历数字 -->
        <ul>
            <li v-for="index in 10">
                {{index}}
            </li>
        </ul>
    </div>
</body>
<script>
    const vm = new Vue({
        el: "#app",
        data: {
            list: ["a", "b", "c"],
            person: { name: "zs", age: 18 },

            courseList: [
                { courseTitle: "web" }, { courseTitle: "java" }
            ]
        },
        methods: {},
    });
</script>

</html>

结果

V-for和key属性_vue.js