利用fadein、fadeout写轮播

<div id="s" style="width:400px;height:300px;position:relative;">
            <div id="s1" style="position:absolute;width:100%;height:100%;background-color:gray;"></div>
            <div id="s2" style="position:absolute;width:100%;height:100%;background-color:green;"></div>
            <div id="s3" style="position:absolute;width:100%;height:100%;background-color:blue;"></div>
        </div>

 var count = 1;
    function huan() {
       
        if (count == 4)
        { count = 1; }
        $("#s" + count + "").fadeIn();
        $("#s" + count + "").siblings().fadeOut();
        count++;
    }

    setInterval("huan()", 1000);