由于浏览器对图层的支持不同，所以首先要确定客户端浏览器的类型。以下代码可用于判断客户端的浏览器和操作系统。
var detect = navigator.userAgent.toLowerCase();
var OS,browser,version,total,thestring;
function getBrowserInfo() {
if (checkIt('konqueror')) {
browser = "Konqueror";
OS = "Linux";
}
else if (checkIt('safari')) browser = "Safari"
else if (checkIt('omniWeb')) browser = "OmniWeb"
else if (checkIt('opera')) browser = "Opera"
else if (checkIt('Webtv')) browser = "WebTV";
else if (checkIt('icab')) browser = "iCab"
else if (checkIt('msie')) browser = "Internet Explorer"
else if (!checkIt('compatible')) {
browser = "Netscape Navigator"
version = detect.charAt(8);
}
else browser = "An unknown browser";
if (!version) version = detect.charAt(place + thestring.length);
if(!OS) {
if (checkIt('linux')) OS = "Linux";
else if (checkIt('x11')) OS = "Unix";
else if (checkIt('mac')) OS = "Mac"
else if (checkIt('win')) OS = "Windows"
else OS = "an unknown operating system";
}
}
function checkIt(string) {
place = detect.indexOf(string) + 1;
thestring = string;
return place;
}
下面看一下网页加载时需要添加的方法。有关网页加载和初始化方法代码如下：
//网页加载调用initialize和getBrowserInfo方法
Event.observe(window, 'load', initialize, false);
Event.observe(window, 'load', getBrowserInfo, false);
//未加载时清空缓存
Event.observe(window, 'unload', Event.unloadCache, false);
//初始化方法
function initialize(){
//调用该方法为该页添加覆盖层和高亮显示层
addLightboxMarkup();
//为每个可高亮显示的元素创建lightbox对象 软件开发网 www.mscto.com
lbox = document.getElementsByClassName('lbOn');
for(i = 0; i < lbox.length; i++) {
valid = new lightbox(lbox[i]);
}
}
// 使用Dom方法创建覆盖层和高亮层
function addLightboxMarkup() {
bod = document.getElementsByTagName('body')[0];
overlay = document.createElement('div');
overlay.id = 'overlay';
lb = document.createElement('div');
lb.id = 'lightbox';
lb.className = 'loading';
lb.innerHTML = '<div id="lbLoadMessage">' +
'<p>Loading</p>' +
'</div>';
bod.appendChild(overlay);
bod.appendChild(lb);
}
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