写一个方法获取滚动条距离窗口顶部的距离

Answer 1

    function getScrollTop(){
        var scrollTop = 0  
        if(document.documentElement&& document.documentElement.scrollTop){
            scrollTop = document.documentElement.scrollTop
        }else if(document.body){
            scrollTop = document.body.scrollTop
        }
        return scrollTop
    }