$lis.each(function (i,target){
            $(target).click(function (){
                console.log(i);
            });
        });
        var arr=[‘aa‘,‘bb‘,‘cc‘];
        $.each(arr,function(i,item){
            console.log(i);// 0 1 2 
            console.log(item);//aa bb cc
        });
        var obj={a:11,b:22,c:33};
        $.each(obj,function(i,item){
            console.log(i);//a b c
            console.log(item);//11 22 33
        });
        $(‘#list li‘).click(function(){
            if ($(this).is(‘.li3‘)) {
                $(this).css(‘background‘,‘green‘);
            }else{
                $(this).css(‘background‘,‘orange‘);
            }
        });

$(‘#btn‘).click(function(){
            $(‘.con‘).slideToggle(1000);
        });
slideToggle() 对被选元素进行滑动隐藏和滑动显示的切换3