jQuery determines which li is currently clicked_jquery

Use $(this).index() to get the subscript of li. The following is an example of style replacement:

$("#aa li").click(function(){
$("#aa li").removeClass("class名字，多个class用空格分开");
$(this).addClass("class名字，多个class用空格分开");
if($(this).index()!=0){
$("#submenu").hide();
}else{
$("#submenu").show();
}
})