var arrF = [2,3,4];

    var arrS = arrF.forEach(function (value,index,a) {  //value:数组的值;index:数组索引,a操作的数组

             a[index]=value+33

    })

    console.log(arrF); //结果:35,36,37

    console.log(arrS)  //结果:undefined

<body >

<div  id="app">

    <input  v-focus  value="" id="inp">

    <input type="text">

</div>

</body>

<script>

    var input = document.querySelectorAll('input');

    input.forEach(function (value,index,a) {

        a[index].value='hahhah';

        value.value="wowoowo"

    })

</script>

let arrF = [2,3,4];

 let arrS = arrF.forEach(function (value,index,a) {

            return value+10

    });

    console.log(arrF); //结果;[2,3,4]

    console.log(arrS) //结果:[12,13,14]

 let arrF = [2,3,4];

    let arrS = arrF.map(function (value,index,a) {

            return a[index]=value+10

    });

    console.log(arrF); //结果:[12,13,14] 这个结果有点不明白

    console.log(arrS) //结果:[12,13,14]