var userAgent = navigator.userAgent.toLowerCase();
var isMac = (/macintosh/.test(userAgent));
var lessIE8 = (/msie (6|7)/.test(userAgent));
var isIE8 = (/msie (8)/.test(userAgent));
var isIE = (/msie/.test(userAgent) && !/opera/.test(userAgent));
var isFF = (/mozilla/.test(userAgent) && !/(compatible|webkit)/.test(userAgent));
var isOpera = (/opera/.test( userAgent ));
var isSafari = (/webkit/.test(userAgent));

var isFF4 = (/firefox\/4\./.test(userAgent) && /mozilla/.test(userAgent) && !/(compatible|webkit)/.test(userAgent));
var isFF5 = (/firefox\/5\./.test(userAgent) && /mozilla/.test(userAgent) && !/(compatible|webkit)/.test(userAgent));

function onlyNumbers(e,allowsComma)
{
    var key = e.charCode || e.keyCode || 0;
    
    var extraCharAllowed = (allowsComma && key == 188);
    
    // allow backspace, tab, delete, arrows, numbers and keypad numbers ONLY
    return ( extraCharAllowed || 
        key == 8 || 
        key == 9 ||
        key == 46 ||
        (key >= 37 && key <= 40) ||
        (key >= 48 && key <= 57) ||
        (key >= 96 && key <= 105)); 
}