CSS按钮高亮的解决方案

.active {
            background-color: aqua;
        }

<div id="list">
    <span>1</span>
    <span>2</span>
    <span>3</span>
    <span>4</span>
    <span>5</span>
</div>

    var a = $("#list span");
    console.log(a[0]);
    for (var i = 0; i < a.length; i++) {
        a[i].index = i;
        a[i].onclick = function () {
            for (var i = 0; i < a.length; i++) {
                a[i].className = ''
            }
            this.className = 'active'
        }
    }