js实现点击那个li那个li就变色

参考文献：https://blog.csdn.net/u014101606/article/details/52318014

<ul id='mu2' style="display: flex;flex-wrap: wrap;margin: 10px;list-style: none;">

<li style="width: 18%;background-color: #F6F6F6;margin: 3px;text-align: center;padding: 2px;">xs

</li><li style="width: 18%;background-color: #F6F6F6;margin: 3px;text-align: center;padding: 2px;">xs

</li><li style="width: 18%;background-color: #F6F6F6;margin: 3px;text-align: center;padding: 2px;">xs

</li><li style="width: 18%;background-color: #F6F6F6;margin: 3px;text-align: center;padding: 2px;">xs

</li><li style="width: 18%;background-color: #F6F6F6;margin: 3px;text-align: center;padding: 2px;">xs

</li>

</ul>

document.getElementById("mu").onclick = function(e){

        e = e || window.event;

        var target = e.srcElement || e.target,

            //tagName = target.tagName.toLowerCase(),

            allLi = document.getElementById("mu").getElementsByTagName("li");

        for(var i=0,len=allLi.length;i<len;i++){

            if(target == allLi[i]){

                allLi[i].style.backgroundColor = "red";

            }else{

                allLi[i].style.backgroundColor = "#EFEFF4";

            }

        }

    };