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Netscape Communicator 4.0 and Internet Explorer 4.0

var isWin95 = navigator.userAgent.indexOf(“Win95”) > -1 ||

navigator.userAgent.indexOf(“Windows 95”) > -1;

But this was only the beginning.

Netscape Communicator 4.0 was released in August of 1997 (the name changed from

Navigator

Communicator

for this version). Netscape remained true to its original user-agent string format:

Mozilla/

AppVersion

(

Platform

;

Security [

;

OS-or-CPU-Description]

)

With version 4.0 on a Windows 98 machine, the user-agent string looked like this:

Mozilla/4.0 (Win98; I)

And as Netscape released patches and fixes for its browser, the AppVersion (accessible through

naviga-

tor.appVersion

) was incremented accordingly, as a user-agent string from version 4.79 indicates:

Mozilla/4.79 (Win98; I)

To Netscape’s credit, the method for detecting the version of Netscape Communicator being used

remained the same.

When Internet Explorer 4.0 was released a short time later, Microsoft did developers a favor by updating

the user-agent string, changing the Mozilla version to 4.0 (which matched Netscape’s latest browser).

Except for this minor modification, IE remained with its original user-agent string format of:

Mozilla/4.0 (compatible; MSIE

[IEVersion]

;

[OS]

)

For example, IE 4.0 running on Windows 98 returned the following user-agent string:

Mozilla/4.0 (compatible; MSIE 4.0; Windows 98)

This change allowed a very simple algorithm to be used when determining if a browser was 4.0-level:

if (parseFloat(navigator.appVersion) >= 4) {

//do 4.0-level stuff here

}

Although IE 4.0 was the only one of the 4.0 family to be released on the Windows platform, IE 4.5 was

released for MacOS shortly thereafter. This gave a glimpse into the future of IE’s user-agent string format.

IE 4.5 for the MacOS stayed true to the IE 4.0 format for user-agent strings, but updated the IE version

number:

Mozilla/4.0 (compatible; MSIE 4.5; Mac_PPC)

The browser version is 4.5, but the Mozilla version is 4.0, forcing developers to adjust their algorithms

when detecting IE/Mac. This is important to keep in mind.

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Browser and Operating System Detection

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