JS-實現導航欄懸停
先布個局：
復制代碼 代碼如下:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<head>
<script type="text/javascript" src="test.js"></script>
<link rel="stylesheet" type="text/css" href="test.css"></link>
<title>Test</title>
</head>
<body>
<div class="main">
<div class="content">1</div>
<div id="nav" class="navigation">
<div class="tab">tab1</div>
<div class="tab">tab2</div>
<div class="tab">tab3</div>
<div class="tab">tab4</div>
</div>
<div class="content">2</div>
<div class="content">3</div>
<div class="content">4</div>
<div class="content">5</div>
<div class="content">6</div>
<div class="content">7</div>
</div>
</body>
</html>
添加簡單的樣式：
復制代碼 代碼如下:
div.main{
width: 800px;
background: #CCC;
margin: 10px auto 0;
position: relative;
}
div.content{
width: 800px;
height: 400px;
background: yellow;
margin: 10px auto 0;
}
div.navigation{
width: 800px;
height: 40px;
background: red;
margin: 4px auto 0;
top: 400px;
left: 0px;
position: absolute;
}
div.tab{
width: 195px;
height: 40px;
background: blue;
float: left;
margin-left: 5px;
}
JS:
復制代碼 代碼如下:
//記錄導航條原來在頁面上的位置
var naviga_offsetTop = 0;
//IE7不識別getElementsByClassName，為了兼容自定義一個
function my_getElementsByClassName(class_name) {
var el = [];
//獲取所有元素
_el = document.getElementsByTagName('*');
//通過className刷選
for (var i=0; i<_el.length; i++ ) {
if (_el[i].className == class_name ) {
el[el.length] = _el[i];
}
}
return el;
}
//導航條，懸停在頂部
function naviga_stay_top(){
var a_navigation_bar = [];
if(document.getElementsByClassName){//Chrome, FF
a_navigation_bar = document.getElementsByClassName("navigation");
} else {//IE
a_navigation_bar = my_getElementsByClassName("navigation");
}
var scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
if( scrollTop > naviga_offsetTop){
a_navigation_bar[0].style.top = scrollTop + "px";
} else {
a_navigation_bar[0].style.top = naviga_offsetTop + "px";
}
}
//給導航條上四個tab，加上點擊事件。
window.onload=function(){
var a_tabs = [];
if( document.getElementsByClassName ){//Chrome, FF
a_tabs = document.getElementsByClassName("tab");
}else{ //IE
a_tabs = my_getElementsByClassName("tab");
}
var a_contents = [];
if( document.getElementsByClassName ){//Chrome, FF
a_contents = document.getElementsByClassName("content");
}else{//IE
a_contents = my_getElementsByClassName("content");
}
a_tabs[0].onclick=function(){
window.scrollTo(0, a_contents[2].offsetTop);
}
a_tabs[1].onclick=function(){
window.scrollTo(0, a_contents[3].offsetTop);
}
a_tabs[2].onclick=function(){
window.scrollTo(0, a_contents[4].offsetTop);
}
a_tabs[3].onclick=function(){
window.scrollTo(0, a_contents[5].offsetTop);
}
//獲取頁面上，導航條到頂部的位置
var a_navigation_bar = [];
if(document.getElementsByClassName){//Chrome, FF
a_navigation_bar = document.getElementsByClassName("navigation");
} else {//IE
a_navigation_bar = my_getElementsByClassName("navigation");
}
naviga_offsetTop = a_navigation_bar[0].offsetTop;
//給滾動條以及鼠標加上滾動事件
// window.onscroll= naviga_stay_top;
// document.onmousewheel= naviga_stay_top;
if( window.attachEvent) //IE
{
window.attachEvent("onmousewheel", naviga_stay_top);
window.attachEvent("onscroll", naviga_stay_top);
document.attachEvent("onmousewheel", naviga_stay_top);
document.attachEvent("onscroll", naviga_stay_top);
} else {//Chrome ,FF
window.addEventListener("mousewheel", naviga_stay_top,false);
window.addEventListener("scroll", naviga_stay_top,false);
document.addEventListener("mousewheel", naviga_stay_top,false);
document.addEventListener("scroll", naviga_stay_top,false);
}
}
不知道什麼原因，在IE上，滾動滾動條或者鼠標滾輪的時候，導航欄會抖動;而在Chrome和FF上有沒有任何問題。還望高人指點。