https://www.jimkhan.co.uk/jsfiles/includes/browser.js

1//---- Set this variable only! ----
2var buildDir = "jsfiles/includes/";
3//---------------------------------
4
5var ie4 = false, ie5_mac = false, ie55 = false;
6var nn4 = false, dom = false, opera = false, safari = false;
7var agent = navigator.userAgent.toLowerCase();
8
9if (agent.indexOf("opera") != -1)
10	opera = true;
11else if (agent.indexOf("safari") != -1)
12	safari = true;
13else if (document.all)
14{
15	var version = parseFloat(agent.substr(agent.indexOf("msie")+5, 3));
16	if (agent.indexOf("mac") != -1 && version >= 5)
17		ie5_mac = true;
18	else
19	{
20		if (version >= 5.5)
21			ie55 = true;
22		else if (version >= 4)
23			ie4 = true;
24	}
25}
26//else if (document.layers)
27else if (navigator.appName == "Netscape" && parseInt(navigator.appVersion) >= 4 && 
28	parseInt(navigator.appVersion) < 5)
29	nn4 = true;
30else if (document.getElementById)
31	dom = true;
32
33var blank = new Image();
34blank.src = buildDir + "blank.gif";
35
36if (ie4)
37	document.write('<script type="text/javascript" src="' + buildDir + 'ie4-build.js"></script>');
38else if (ie5_mac)
39	document.write('<script type="text/javascript" src="' + buildDir + 'ie5m-build.js"></script>');
40else if (ie55)

41	document.write('<script type="text/javascript" src="' + buildDir + 'ie55-build.js"></script>');
42else if (nn4)
43	document.write('<script type="text/javascript" src="' + buildDir + 'ns4-build.js"></script>');
44else if (dom)
45	document.write('<script type="text/javascript" src="' + buildDir + 'dom-build.js"></script>');
46else if (opera)
47	document.write('<script type="text/javascript" src="' + buildDir + 'op7-build.js"></script>');
48else if (safari)
49	document.write('<script type="text/javascript" src="' + buildDir + 'saf-build.js"></script>');
50else
51{
52	alert("Your browser doesn't support this script.");
53	location.href = buildDir + "upgrade.html";
54	document.write('<script type="text/javascript" src="' + buildDir + 'no-build.js"></script>');
55}