$.browser()

$.browser() returns Boolean
Contains flags for the useragent, read from navigator.userAgent. Available flags are: safari, opera, msie, mozilla
This property is available before the DOM is ready, therefore you can use it to add ready events only for certain browsers.
There are situations where object detections is not reliable enough, in that cases it makes sense to use browser detection. Simply try to avoid both!
A combination of browser and object detection yields quite reliable results.

Example:

Returns true if the current useragent is some version of microsoft's internet explorer
$.browser.msie

Example:
Alerts "this is safari!" only for safari browsers
if($.browser.safari) { $( function() { alert("this is safari!"); } ); }