// 说明 ：用 Javascript 实现锚点(Anchor)间平滑跳转 

    // 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  = 0;     
    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); 
     }