function getBrowser()
{
var
Browsers = ["MSIE", "Firefox", "Safari", "Chrome", "Opera"],
Agent = navigator.userAgent;
i = Browsers.length - 1;
for (i; i > -1 && Agent.indexOf(Browsers[i]) === -1; i--);
return Browsers[i]
}
document.write(getBrowser());
/*
run:
Firefox
*/