Javascript; Browser Detection and Page Redirection

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A recent project was ...
using Internet Explorer 5.5 as ... of choice.
Aware of browser ... viewing theweb page using three other commonly used ...
... 4 A recent project was developed using Internet Explorer 5.5 as thebrowser of choice.
Aware of browser incompatibilities, viewing theweb page using three other commonly used browsers, InternetExplorer 4.0, Netscape Navigator 6.1, and Netscape Navigator 4.7revealed some 'distortions'. This was mainly due to whether or nota particular browser could interpret style sheets, and if so how thestyle sheets were interpreted.
It was apparent that the page code either needed to be downgradedto the 'lowest common denominator' or alternative versions of theweb page were needed for Netscape 6.1, Netscape 4.7, andInternet Explorer 4.0. Therefore, a version optimized for Netscape6.1 was created, as well as another version compatible for bothNetscape 4.7 and Internet Explorer 4.0.
(This was before InternetExplorer 6.0 and Netscape 6.2 were available.) Review of several current web sites and textbooks on Javascriptpresented different approaches to writing script to first detect auser's browser, and then depending on the browser and version,to redirect the user to a specific page. In this particular case, noneof the recommendations or solutions were what was needed.
Aftera good deal of testing and re-testing, the following script exampleswere assembled. Below are five different examples / variations of some Javascriptthat is to be placed on a page that is optimized for Internet Explorer5.5.
These scripts will then automatically detect the visitor's browserand version, and then automatically direct the particular browser inone of three directions. They are; If a visitor is using Internet Explorer 5.5, to remain on the current page.If a visitor is using Netscape 6.1, to be redirected to a page that hasbeen optimized for Netscape 6.1.If a visitor is using Internet Explorer 4.0 or Netscape 4.7, to beredirected to a third page that has been written specifically foreither of these browser versions.
Explanatory discussion follows the script examples. #1



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---------------------------------------------------------------Any of these five different scripts can be utilized.
These have been compiled after many attempts at using other suggestedscripts that either were too limited, were not applicable toidentifying version 5 and higher browsers, or just did not seem towork as anticipated.All these scripts are a series of conditional statements, which areread by the visitor's browser when the web page 'ie55.htm' isloaded.1. The browser reads the first statement and if it is Netscape 6.1,it is redirected to the page written specifically for Netscape 6.1.If not,2.
The browser reads the next statement and if it is Netscape 4.7,it is redirected to the page written for the 'number 4’ version ofeither Internet Explorer or Netscape Navigator. If not,3.
The browser reads the next statement and if it is Internet Explorer4.0, it too is redirected to the page written for the 'number 4'version of either Internet Explorer or Netscape Navigator.And lastly,4. If none of the statements apply, the browser will remain on thesame page that contains the script and proceed to read theremainder of the page.
Next are several observations made after consulting several resources(online and in print) and conducting many 'trial and error' sessions. Peculiarities encountered that caused difficulties include;1.
Regarding the line that identifies a browser's version number (navigator.appVersion.indexOf(" ") != -1) Internet Explorer; you must use "MSIE 4", not "MSIE 4.0", "4", or"4.0". The same is true whether or not this additional ‘if’ statement,(navigator.appName.indexOf("Internet Explorer") != -1), is includedas in #1.
Use "MSIE 5" to identify Internet Explorer 5.5. **Seebelow for more about Internet Explorer and version numbers.Version 5.5 does not fall under the category of version 5 or higher.Netscape Navigator; in this statement either "5.0" or "5" will workwith Netscape 6.1 resulting in directing the browser to the pageoptimized for Netscape 6.1.
if (navigator.appName.indexOf("Netscape") != -1) { if (navigator.appVersion.indexOf("5.0") != -1) window.location="nn61.htm"; }But in this statement, "5.0" must be used. "5" results in Netscape 4.7being directed to the page optimized for Netscape 6.1 instead of thepage optimized for Netscape 4.7.
The reason is unknown. Thispeculiarity was discovered through 'trial and error'.
if (navigator.appName.indexOf("Netscape") != -1) { if (navigator.appVersion.indexOf("5.0") == -1) window.location="ienn4.htm"; }** NOTE: Attempting to separate browsers based upon their versionnumber is not as straight forward as it might seem. The reason is thatboth Internet Explorer 4.0 and Internet Explorer 5.5 have the sameversion number of 4! Also Netscape 6.1 has a version number of 5!So trying to detect and then select browsers based on version numbersresults in confusion.
In particular The version number of '5 and higher' will exclude Internet Explorer 5.5The version number of '4 and lower' will include Internet Explorer 5.5The version number of '6 and higher' will exclude Netscape 6.1 2. Regarding the line that identifies a browser's name(navigator.app.Name.indexOf(" ") != -1) Internet Explorer; you must use "Internet Explorer", "Microsoft", or"Microsoft Internet Explorer".
"MSIE" is not recognized. 3.
All of these browsers, Netscape 4.7 and 6.1, and InternetExplorer 4.0 and 5.5, have the same code name of Mozilla. Therefore these browsers can not differentiated based on theircode name.
Conclusions;Remember that these scripts are to be placed on the page that hasbeen optimized for viewing using the Internet Explorer 5.5 browser. If a Netscape 6.1 browser is being used, the visitor is automaticallyredirected to the page that has been optimized for Netscape 6.1.If a Netscape 4.7 browser is being used, the visitor is automaticallyredirected to the page that has been optimized for either Netscape4.7 or Internet Explorer 4.0.
If an Internet Explorer 4.0 browser is being used, the visitor isautomatically redirected to the page that has been optimized foreither Netscape 4.7 or Internet Explorer 4.0. If none of these three 'if' conditional statements are true, the browserwill remain on the present page and will continue on with interpretingthat page, in this case the page that has been optimized for InternetExplorer 5.5.
To use these scripts, remember to replace the fictitious pages"nn61.htm", "ienn4.htm", and "ie55.htm" with your actual pages.Also if using one of these scripts on a page that is created forviewing using a browser other than IE 5.5, further adjustments willbe necessary, as well as, then re-testing the script(s).Remember that some of the other browser types that are in useinclude, i.e. AOL, Netscape Navigator 3.0 or lower, InternetExplorer 3.0 or lower, Opera (various versions), Web TV, Lynx,Konqueror.
All of these are used in small numbers and whether onewants to address each one of these browsers is an individual decision.There are different web sites that contain statistics on browser usagethat can be reviewed. The best source of information on the actualbrowsers that are used to view your web site are your own visitor logs.Check those as they may or may not agree with other published webstatistics.Obviously Intranets are a special environment and one in which thepages must be optimized for the particular browser that is in use onthe Intranet machines.
This is a much easier situation to have to contendwith.Unfortunately until the 'browser wars' come to an end and an 'acrossthe board acceptance' of the W3C's guidelines for coding is the rule,browser incompatibilities will continue to influence web page construction. Source: Free Articles from ArticlesFactory.com .