jquery【点击】导航按钮的来回切换

先获取元素的属性值，根据属性值进行判断，点击时对属性进行设置

<i class="layui-icon layui-icon-shrink-right" id="nav_but" onclick="but_test()"></i>
<script>
function but_test(){
var _val = $("#nav_but").attr("class");
if(_val == "layui-icon layui-icon-shrink-right"){
$("#nav_but").attr("class","layui-icon layui-icon-close");
// _val = "layui-icon layui-icon-close";
}else{
$("#nav_but").attr("class","layui-icon layui-icon-shrink-right");
}
}
</script>