判斷Browser是IE還是FireFox

JDP

// IE navigator.appName = "Microsoft Internet Explorer" navigator.appVersion = 4
// FireFox navigator.appName = "Netscape" navigator.appVersion = 5

IE4 = (navigator.appName == "Microsoft Internet Explorer" && parseInt(navigator.appVersion) >= 4);
NN4 = (navigator.appName == "Netscape" && parseInt(navigator.appVersion) >= 4);

後續使用方法：
if (IE4) xxxxxxxxxxxxxxxx;
else if (NN4) xxxxxxxxxxxxxx;