function?getclsname(cls,parent){
			var?oparent=parent?document.getElementById(parent):document;
			var?eles=[];
			var?elements=oparent.getElementsByTagName("*");
			for(var?i=0;i<elements.length;i++){
				if(elements[i].className==cls){
					eles.push(elements[i]);
				}
			}
			return?eles;
		}
		
			window.onload=function(){
				window.onscroll=function(){
					var?top=document.documentElement?document.documentElement.scrollTop:document.body.scrollTop;
					var?menus=document.getElementById("menu").getElementsByTagName("a");
					var?items=getclsname("item");
					var?currentid="";
					for(var?i=0;i<items.length;i++){
						var?it=items[i];
						var?itemstop=it.scrollTop;
						if(top>itemstop-200){
							currentid=it.id;
						}else{
							break;
						}
					}
					if(currentid){
						for(var?j=0;j<menus.length;j++){
							var?mu=menus[j];
							var?href=mu.href.split("#");
							if(href[href.length-1]!=currentid){
								mu.className="";
							}else{
								mu.className="current";
							}
						}
					}
				}
			}

非常感謝！