导航全局滑动JavaScript

/// <summary>
/// 前往某个指定ID的锚点
/// </summary>
/// <param name="id">锚点ID</param>
/// <param name="cutHeight">稍上或稍下的高度值</param>
function goTo(id, cutHeight) {
    //IE6下会读不到值
    // alert("ID=" + id + "的标签与顶部的实际高度距离为：" + document.getElementById(id).offsetTop);

    var h = document.getElementById(id).offsetTop;
    if (h == 0)
        h = 20300;

    scroll(0, h - cutHeight);
}

//↓↓↓↓↓导航全局滑动↓↓↓↓↓/////start
var oldCurrent = 0;
var oldtop;
var sindex = 0;
function movebox(id) {
    sindex++;
    var daohang = document.getElementById(id);
    var objleft = getObUpperLeft(daohang, 1);
    var objtop = getObUpperLeft(daohang, 2);
    if (sindex == 1)
        oldtop = objtop;
    var cha = getPageScroll2() - oldtop;
    if (cha <= oldCurrent) {
    
        if (cha > 0) {
           daohang.style.display = "Block";
            daohang.style.position = "fixed";
            daohang.style.top = "0px";
            try {
                ////判断IE6.0不同写法
                var browser = navigator.appName;
                var b_version = navigator.appVersion;
                var version = b_version.split(";");
                var trim_Version = version[1].replace(/[ ]/g, "");
                if (browser == "Microsoft Internet Explorer" && trim_Version == "MSIE6.0") {
                    daohang.style.position = "absolute";
                    daohang.style.left = objleft + "px";
                    daohang.style.top = getPageScroll2() + "px";
                }
            }
            catch (e) {

            }
        }
        else {
            daohang.style.position = "static";
        }
        
        
     }
    else {
       daohang.style.display = "none";
    }
    
    oldCurrent = cha;
   
}

window.onscroll = function() {
    movebox("daohang");
}

//获取对象坐标
function getObUpperLeft(obj, type) {
    var curLeft = curTop = 0;
    if (obj.offsetParent) {
        curLeft = obj.offsetLeft;
        curTop = obj.offsetTop;
        while (obj = obj.offsetParent) {
            curLeft += obj.offsetLeft;
            curTop += obj.offsetTop;
        }
    }
    if (type == 1)
        return curLeft;
    else if (type == 2)
        return curTop;
}

//获取浏览器滚动条高度
function getPageScroll2() {

    var yScroll;
    if (self.pageYOffset) {
        yScroll = self.pageYOffset;
    } else if (document.documentElement && document.documentElement.scrollTop) {
        yScroll = document.documentElement.scrollTop;
    } else if (document.body) {
        yScroll = document.body.scrollTop;
    }

    return yScroll;
}

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