请大神帮忙看一下代码问题出在哪

源自：6-4 编程练习

请大神帮忙看一下代码问题出在哪

字数不够，我把后面的HTML删了

<!DOCTYPE html>

<html>

<head>

<title>地狗购物网——网页定位导航效果</title>

<style>

* {

margin: 0;

padding: 0;

}

body {

font-size: 12px;

line-height: 1.7;

}

li {

list-style: none;

}

#content {

width: 800px;

margin: 0 auto;

padding: 20px;

}

#content h1 {

color: #0088bb;

}

#content .item {

padding: 20px;

margin-bottom: 20px;

border: 1px dotted #0088bb;

}

#content .item h2 {

font-size: 16px;

font-weight: bold;

border-bottom: 2px solid #0088bb;

margin-bottom: 10px;

}

#content .item li {

display: inline;

margin-right: 10px;

}

#content .item li a img {

width: 230px;

height: 230px;

border: none;

}

#menu {

position: fixed;

top: 100px;

left: 50%;

margin-left: 400px;

width: 80px;

}

#menu ul li a {

display: block;

margin: 5px 0;

font-size: 14px;

font-weight: bold;

color: #333;

width: 80px;

height: 50px;

line-height: 50px;

text-decoration: none;

text-align: center;

}

#menu ul li a:hover,

#menu ul li a.current {

color: #fff;

background: #0088bb;

}

/*ie6 hack*/

* html, * html body {

background-image: url(about:blank);

background-attachment: fixed;

}

* html #menu {

/*position: fixed;*/

position: absolute;

top: expression(((e=document.documentElement.scrollTop)?e:document.body.scrollTop)+100+'px');

}

</style>

//定义getByClassName函数，让函数实现根据class name获取对象并返回

// function getByClassName( obj, cls){

// var elements = obj.getElementsByTagName("*");

// var result = [];

// for (var i = 0;i<elements.length;i++){

// if(elements[i].className == cls ){

// result.push(elements[i]);

// }

// return result;

// }

// function hasClass( obj, cls ){

// return obj.className.match(new RegExp("(\\s|^)" + cls + "(\\s|$)"));

// }

// function removeClass( obj, cls ){

// if( hasClass( obj, cls )){

// //remove

// var reg = new RegExp("(\\s|^)" + cls + "(\\s|$)");

// obj.className = obj.className.replace(reg, "");

// }

// //定义getByClassName函数，让函数实现给对象增加class

// function addClass( obj, cls ){

// if( !hasClass( obj, cls )){

// obj.className += " " + cls;

// }

//zhengque

function getByClassName(obj, cls){

var elements = obj.getElementsByTagName("*");

var result = [];

for(var i = 0; i < elements.length; i++){

if(elements[i].className == cls){

result.push(elements[i]);

}

return result;

}

function hasClass( obj, cls ){

return obj.className.match(new RegExp("(\\s|^)" + cls + "(\\s|$)"));

}

function removeClass( obj, cls ){

if( hasClass( obj, cls )){

//remove

var reg = new RegExp("(\\s|^)" + cls + "(\\s|$)");

obj.className = obj.className.replace(reg, "");

}

//定义getByClassName函数，让函数实现给对象增加class

function addClass(obj, cls){

if(!hasClass(obj, cls)){

obj.className += " " + cls;

}

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 = getByClassName(document.getElementById("content"), "item");

var currentId = "";

for ( var i=0; i< items.length; i++ ){

var _item = items[i];

var _itemTop = _item.offsetTop;

if( top > _itemTop - 200 ){

currentId = _item.id;

} else {

break;

}

//请补充此处代码，给正确的menu下的a元素class赋值current

// if(currentId){

// for(var j = 0; j < menus.length; j++){

// var _menu = menus[j];

// var _href = _menu.href.split("#");

// if(_href[_href.length - 1] != currentId){

// removeClass(_menu, "current");

// } else {

// addClass(_menu, "current");

// }

//zhengque

if( currentId){

for (var j = 0;j < menus.length; j++){

var _menu = menus[j];

var _href = _menu.href.split("#");

if( _href[_href.length - 1] != currentId){

removeClass( _menu, "current");

}else{

addClass( _menu, "current");

}

</script>

</head>

<body>

<ul>

提问者：第二热情 2016-09-09 00:42

请大神帮忙看一下代码问题出在哪

个回答