// http://techpatterns.com/downloads/javascript_browser_detection.php#simple

var d, dom, ie, ie4, ie5x, moz, mac, win, lin, old, ie5mac, ie5xwin, op;

d = document;
n = navigator;
na = n.appVersion;
nua = n.userAgent;

win = ( na.indexOf( 'Win' ) != -1 );
mac = ( na.indexOf( 'Mac' ) != -1 );
lin = ( nua.indexOf( 'Linux' ) != -1 );

if ( !d.layers ){
	dom = ( d.getElementById );
	op = ( nua.indexOf( 'Opera' ) != -1 );
	konq = ( nua.indexOf( 'Konqueror' ) != -1 );
	saf = ( nua.indexOf( 'Safari' ) != -1 );
	moz = ( nua.indexOf( 'Gecko' ) != -1 && !saf && !konq);
	ie = ( d.all && !op ); ie4 = ( ie && !dom );
	/* ie5x tests only for functionality. ( dom||ie5x ) would be default settings.
	Opera will register true in this test if set to identify as IE 5 */
	ie5x = ( d.all && dom );
	ie5mac = ( mac && ie5x );
	ie5xwin = ( win && ie5x );
} 
/* Here is a sample use of the browser detector, it would load a browser specific stylesheet for certain 
unsupported or improperly supported mac ie 5 css styles. The depth variable is 
used so that the javascript library file can be used from anywhere in the 
website, you simply insert the depth of the file like this, ...

		<head>
		<title>Browser information Page</title>
		
		<meta http-equiv = "Content-Type" content = "text/html; charset = iso-8859-1" />
		<link rel = "stylesheet" type = "text/css" href = "/styles/layout.css" />
		<script type="text/javascript" src="/scripts/browser_info.js" />
		<script type="text/javascript>
			browser_css('/');
		</script>
		</head>

in the head of the web page after the js file is loaded.
Or if you are always referring your site to the root, you wouldn't need that 
and could delete the depth variable and just use the absolute path to the root.

function browser_css( ) {
	d = document;
	if ( saf ) {
		d.write('<link rel = "stylesheet" type = "text/css" href="/styles/safonly.css" />');
	}
}
*/