[Script] How to detect client's browser type and version (only support IE, Firefox & Netscape)?

I hypothesize you want to recognize client's type and version. To approach this goal, you should take advantage of navigator object.

The navigator object has the following properties:

1. appCodeName
   The code name of the browser.
2. appName
   The name of the browser (ie: Microsoft Internet Explorer).
3. appVersion
   Version information for the browser (ie: 4.75 [en] (Win98; U)).
4. cookieEnabled
   Boolean that indicates whether the browser has cookies enabled. IE4 and NS6+.
5. language
   Returns the default language of the browser version (ie: en-US). NS4 and NS6+ only.
6. mimeTypes[]
   An array of all MIME types supported by the client. NS4 and NS6+ only. Array is always empty in IE.
7. platform[]
   The platform of the client's computer (ie: Win32).
8. plugins
   An array of all plug-ins currently installed on the client. NS4 and NS6+ only. Array is always empty in IE.
9. systemLanguage
   IE4+ property that returns the default language of the operating system. Similar to NS's language property.
10. userAgent
    String passed by browser as user-agent header. (ie: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1))
11. userLanguage
    IE4+ property that returns the preferred language setting of the user. Similar to NS's language property.

Practice 1 - Detect client's browser type:

var typeBrowser;
if(navigator.userAgent.indexOf("MSIE")>-1)
typeBrowser = "MS Internet Explorer";
else if(navigator.userAgent.indexOf("Firefox")>-1)
typeBrowser = "FireFox";
else if(navigator.userAgent.indexOf("Netscape")>-1)
typeBrower = "Netscape";
alert("Your browser is " + typeBrowser);

Practice 2 - Detect client's brower version:

var BVersion,temp;
if(navigator.userAgent.indexOf("MSIE")>-1){
temp = navigator.appVersion.split("MSIE");
//because the value of navigator.userAgent in IE is like: 4.0 (compatible; MSIE 5.5; Windows 98; Hotbar 3.0)
BVersion = parseFloat(temp[1]);
}
else if(navigator.userAgent.indexOf("Firefox")>-1){
temp = navigator.appVersion.split("Firefox/");
//because the value of navigator.userAgent in IE is like: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4
BVersion = parseFloat(temp[1]);
}
else if(navigator.userAgent.indexOf("Netscape")>-1){
temp = navigator.appVersion.split("Netscape/");
//because the value of navigator.userAgent in IE is like: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax)
BVersion = parseFloat(temp[1]);
}
alert("The version of your browser is " + BVersion + " or above");

[Script] How to estimate the amount of day in February?

To implement this function, you should understand when February has 29 days.
February has 29 days in any year evenly divisible by four, EXCEPT for centurial years which are not also divisible by 400.

After you understand the definition, the implement will become very easy:

function daysInFebruary (year){
return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}

[Script] Abstract the keyCode on Firefox

To abstract the key value which users press on their keyboard, IE supports a method to approach this goal.

onkeypress="window.event.keyCode";

But FireFox does not support window.event. For cross-platform, We have to revise this method.

onkeypress="jsGetKeyCode(event)"
...
jsGetKeyCode(e){
var keyCode = window.event ? e.keyCode : e.which;
}