滚动条事件

window.onscroll = function (ev) {
        //console.log("距离顶部的高度："+$(document).scrollTop());
        var heightY = $(document).scrollTop();
        var x = $(document).scrollLeft();
        if(heightY > 0){
            console.log("距离顶部的高度："+heightY);
            $("#threadId").css("position","fixed");
        }
        if(x > 0 ){
            console.log("距离左边："+x);
            $("#threadId").css("position","static");
        }
    }