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JavaScript / DHTML / AJAX Discussion Thread
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May 29th, 2007

Hmm... Javascript error, or Mozilla stupidity?

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I wrote this simple code to return my browser's name, because I've never tested this in Firefox:

JavaScript / DHTML / AJAX Syntax (Toggle Plain Text)
<html> <body>
<script type="text/javascript">
var browser=navigator.appName
var b_version=navigator.appVersion
var version=parseFloat(b_version) document.write("Browser: "+ browser)
document.write("<br>")
document.write("Version: "+ version)
</script>
</body> </html>
<html> <body>
<script type="text/javascript">
var browser=navigator.appName
var b_version=navigator.appVersion
var version=parseFloat(b_version) document.write("Browser: "+ browser)
document.write("<br>")
document.write("Version: "+ version)
</script>
</body> </html>

In, Firefox, it returns "Netscape 5." I uploaded a screen shot.

Error?

*sorry for all the blacked out things in the screenshot. You can never be too careful*

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Last edited by linux; May 29th, 2007 at 9:40 pm.

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linux

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Posting Shark

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May 29th, 2007

Re: Hmm... Javascript error, or Mozilla stupidity?

Hm, I thought perhaps you might have wierd browser identification settings.. But apparently not; I tested that code in Firefox 2, and in Opera 9 ( which can pretend to be other browsers; and is pretending to be Mozilla today ). In both cases; Netscape 5 is given back, as per your example. I imagine that this is an attempt to indicate that Firefox and Netscape are compatible on some level...

The userAgent string is perhaps more useful; it's more difficult to use, because you have to parse it manually, or at least search for known indicators within it:

'Real' Firefox
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1) Gecko/20061010 Firefox/2.0

Opera Faking Mozilla
Mozilla/5.0 (X11; Linux i686; U; en) Opera 9.02

Opera REALLY Faking Mozilla
Mozilla/5.0 (X11; Linux i686; U; en; rv:1.7.5) Gecko/20041110

JavaScript / DHTML / AJAX Syntax (Toggle Plain Text)
(ignore my semicolons if you don't use 'em)
<html> <body>
<script type="text/javascript">
var u_agent=navigator.userAgent;
var browser=navigator.appName;
var b_version=navigator.appVersion;
var version=parseFloat(b_version);
document.write("UserAgent: "+ u_agent);
document.write("<br>");
document.write("Browser: "+ browser);
document.write("<br>");
document.write("Version: "+ version);
</script>
</body> </html>
(ignore my semicolons if you don't use 'em)
<html> <body>
<script type="text/javascript">
var u_agent=navigator.userAgent;
var browser=navigator.appName;
var b_version=navigator.appVersion;
var version=parseFloat(b_version);
document.write("UserAgent: "+ u_agent);
document.write("<br>");
document.write("Browser: "+ browser);
document.write("<br>");
document.write("Version: "+ version);
</script>
</body> </html>

MattEvans

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May 30th, 2007

Re: Hmm... Javascript error, or Mozilla stupidity?

Thanks, it helps a lot.

linux

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Posting Shark

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Jun 1st, 2007

Re: Hmm... Javascript error, or Mozilla stupidity?

Very interesting!!!!!!

I tried the 2nd script written by MattEvans and it said i have IE4!!

Quote ...

Browser: Microsoft Internet Explorer
Version: 4

I have 6

Anyway to definetly verify this??

The first script didnt do anything when i went to it (Linux's script)

Last edited by The Dude; Jun 1st, 2007 at 6:35 pm.

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Jun 1st, 2007

Re: Hmm... Javascript error, or Mozilla stupidity?

Look at the full userAgent string. It's weird though; this is for Opera identifying as Internet Explorer. Internet Explorer 6.0 under Wine (Linux) says similar. I can't (be bothered to) go on 'real' MS Windows:

JavaScript / DHTML / AJAX Syntax (Toggle Plain Text)
UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; X11; Linux i686; en)
UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; X11; Linux i686; en)

The 'Mozilla/4.0' part is totally misleading again; the only clue is the MSIE 6.0 part... Which, when compared with the other userAgent strings; doesn't even appear in the same relative position in the string as 'Firefox' or 'Opera' does... Weird indeed.

Using browser detection for anything more than trivial isn't a good idea; partly because it's clearly diffiicult to get a version and browser application that are correct. Even something as obviously neccessarily standard as this; isn't well standardized (userAgent, appName, version give conflicting information, the userAgent string isn't in a standard order etc ).

Another reason why it's bad; is because some users give deliberately incorrect browser identification. For example, one of the websites I have to log onto frequently uses a check like: "is browser netscape X or ie Y? come in; else? sorry! your browser version is out-of-date." - Not so; my browser just isn't one of those two. So I ask it to pretend that it is (by sending a different userAgent string and appName) and in I go; often leaving that identification 'incorrect' for a while after.

Finally; browser version doesn't specifically (or manageably) indicate support or lack of support for any aspect of Javascript... I suppose it could be useful in solving misrepresentations of CSS on different browsers; although, even there, there are CSS-only hacks to isolate FF/Opera (and they can be inverted back to isolate IE via ordered overwriting rules).

See this for a bit more info about 'object detection' instead of browser detection:
http://www.quirksmode.org/js/support.html
And this, if your certain, shows a more complete parser for the appname/useragent return:
http://www.quirksmode.org/js/detect.html

NOTE: First script from linux (the user =P) has probably a copy-paste + upload + parse error:

JavaScript / DHTML / AJAX Syntax (Toggle Plain Text)
var version=parseFloat(b_version) document.write("Browser: "+ browser)
var version=parseFloat(b_version) document.write("Browser: "+ browser)

Should be on two lines:

JavaScript / DHTML / AJAX Syntax (Toggle Plain Text)
var version=parseFloat(b_version)
document.write("Browser: "+ browser)
var version=parseFloat(b_version)
document.write("Browser: "+ browser)

((A problem that's easily solved forever by not ommiting the optional semicolon after each line!!))

Last edited by MattEvans; Jun 1st, 2007 at 9:41 pm.

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