用 Javascript 实现锚点(Anchor)间平滑跳转

<script type="text/javascript">
// 说明 ：用 Javascript 实现锚点(Anchor)间平滑跳转
// 来源 ：ThickBox 2.1
// 整理 ：Yanfu Xie [xieyanfu@yahoo.com.cn]
// 网址 ：http://www.codebit.cn
// 日期 ：07.01.17
// 转换为数字
function intval(v) {     v = parseInt(v);     return isNaN(v) ? 0 : v; }  
// 获取元素信息
function getPos(e) {
    var l = 0;
    var t  = -111;
    var w = intval(e.style.width);
    var h = intval(e.style.height);
    var wb = e.offsetWidth;
    var hb = e.offsetHeight;
    while (e.offsetParent){
        l += e.offsetLeft + (e.currentStyle?intval(e.currentStyle.borderLeftWidth):0);
        t += e.offsetTop  + (e.currentStyle?intval(e.currentStyle.borderTopWidth):0);
        e = e.offsetParent;
    }
        l += e.offsetLeft + (e.currentStyle?intval(e.currentStyle.borderLeftWidth):0);
        t  += e.offsetTop  + (e.currentStyle?intval(e.currentStyle.borderTopWidth):0);
    return {x:l, y:t, w:w, h:h, wb:wb, hb:hb};
}  
// 获取滚动条信息
function getScroll(){
    var t, l, w, h;
    if (document.documentElement && document.documentElement.scrollTop) {
        t = document.documentElement.scrollTop;
        l = document.documentElement.scrollLeft;
        w = document.documentElement.scrollWidth;
        h = document.documentElement.scrollHeight;
        } else if (document.body) {
            t = document.body.scrollTop;
            l = document.body.scrollLeft;
            w = document.body.scrollWidth;
            h = document.body.scrollHeight;
    }
return { t: t, l: l, w: w, h: h }; }  
// 锚点(Anchor)间平滑跳转
function scroller(el, duration) {
    if(typeof el != 'object') {
        el = document.getElementById(el); }
        if(!el) return;
        var z = this;
        z.el = el;
        z.p = getPos(el);
        z.s = getScroll();
        z.clear = function(){window.clearInterval(z.timer);z.timer=null};
        z.t=(new Date).getTime();
        z.step = function(){
            var t = (new Date).getTime();
            var p = (t - z.t) / duration;
            if (t >= duration + z.t) {
                z.clear();
                window.setTimeout(function(){z.scroll(z.p.y, z.p.x)},13);
                } else {
                    st = ((-Math.cos(p*Math.PI)/2) + 0.5) * (z.p.y-z.s.t) + z.s.t;
                    sl = ((-Math.cos(p*Math.PI)/2) + 0.5) * (z.p.x-z.s.l) + z.s.l;
                    z.scroll(st, sl);
                }
};
z.scroll = function (t, l){window.scrollTo(l, t)};
z.timer = window.setInterval(function(){z.step();},13); }
</script>