将类数组转换为数组的方法

<script>
    var wrap= document.getElementsByClassName('wrap')[0];
    var wrapChildren = wrap.getElementsByTagName('div');
    console.log(wrapChildren); //HTMLCollection(4) [div, div, div, div]
    /*
        用原生js获取的元素级  elementcollection,nodeList
        是一个类数组
    */

    /*定义一个空数组，然后push*/
    /*let arr = [];
        for(let item of wrapChildren){
            arr.push(item);
        }
        console.log(arr);
    */

    /*Array.from 类数组-->数组*/
    /*
        var trueArray =  Array.from(wrapChildren);
        console.log(trueArray);
    */

    /*...运算符*/
    /*
        var trueArray = [...wrapChildren];
        console.log(trueArray);
     */

    /*apply的第二个参数可以是数组，也可以是类数组*/
    /*
        var trueArray =  [].concat.apply([],wrapChildren);
        console.log(trueArray);
    */

    var trueArray = Array.prototype.slice.call(wrapChildren);
    console.log(trueArray);
</script>