//use $.platform.<platformname> to return true/false
var userOSAgent = navigator.userAgent.toLowerCase();
// Figure out what browser is being used
jQuery.platform = {
        mac: /mac/.test(userOSAgent),
        osx: /mac os x/.test(userOSAgent),
        win: /win/.test(userOSAgent),
        linux: /linux/.test(userOSAgent)
};