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<p id="box">
    <ul>
        <li v-for="val in arr" track-by="$index">
            {{val}}
           
        </li>
    </ul>
</p>

var vm=new Vue({
    el:'#box',
    data:{
       arr:['apple','banana','orange']
    },
    methods:{
        
    }
});
對(duì)于arr里面的$index 和 $key  在1.0之內(nèi)的版本可以使用，在2.0之后就摒棄了，引入框架版本的時(shí)候一定要注意，在2.0還可以用  v-for="（val，index） in arr"   {{index}}

Don’t quite understand what it means?

Do you want to use v-for to display it on the page?

Or is it?

Object.keys obtains the array composed of the keys of this object, v-for traverses the array, and obtains the fields in the form of obj[k]

<p id="box">
    <ul>
        <li v-for="(val,key) in arr" track-by="$index">
            {{key}}:{{val}}  //key是鍵，val是值           
        </li>
    </ul>
</p>

var vm=new Vue({
    el:'#box',
    data:{
       arr:['apple','banana','orange']
    }
});

v-for = ‘(item, index) in items’
items array
item array item
index array item corresponding subscript
Code must be wrapped in quotes

<p v-for="(val, key) in object"></p>