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How to Determine the Browser Type and Version
Often you will want to send content to the client
only if you know their browser can support it. You may already have created pages that are
designed to work only in IE and Netscape, version 4 or greater. Or for example you
may have situations where a specific browser type and or version creates a page layout
problem. In this lesson we present the technique used to detect specific browsers
that you want to handle things differently for.
For starters, assume you receive complaints that your favorite shade
of blue used for some font text on your page is extremely difficult to read when viewed on
WebTV (colors are typically an issue with WebTV due to contrast and other problems).
What are you do to - remove the blue color all together? Change it for a
boring share of grey? Of course not!
The trick here is first finding a alternative color suitable for
viewing on WebTV, and only using that color when the visitor is using a WebTV browser.
Otherwise you use your blue font as originally planned. Here's how you would
implement that:
filename=/browserhawk/bhwebtv.asp
<%
set bh = server.createobject("cyScape.browserObj")
if (bh.browser = "WebTV") then
fontColor = "003366" 'a suitable alternate color for WebTV folks only
else
fontColor = "000066" 'your favorite shade of blue for all folks
end if
%>
<html>
<head>
<title></title>
</head>
<body>
<p>Welcome to my page. The <font color="<%=fontColor%>important" text</font>is highlighted
for your convenience. </p>
</font>
</body>
</html>
This technique of testing for a specific browser type is also useful
if you have specific tags and scripts that only work with certain browsers. For
example, say you had certain pages that required Netscape or IE versions 4 or higher.
Instead of going through and conditionally including all the v4-only tags, scripts and
objects, this example will show how to use this technique to detect when a browser is not
Netscape or IE v4 or higher, and redirect the user to an alternate page suitable for the
other browsers.
filename=/browserhawk/bhaltpage.asp
<%
set bh = server.createobject("cyScape.browserObj")
if (bh.majorver >=4 ) and (bh.Browser ="IE" or bh.Browser ="Netscape") then
else
response.redirect("PageForNonIEorNNv4.asp")
end if
set bh = nothing
%>
<html><body> </body></html>
Remember that the response.redirect code should go before any of the
HTML content on the page. You can keep this check script in a separate file, and include
it at the top of all pages within an application.
Another example is the title attribute for HTML elements which,
currently, is only supported by IE 4 or greater. While the title attribute degrades fine
in other browsers, it is sometimes desirable to limit the amount of superfluous code being
sent to the browser... regardless of how insignificant it may seem. This example will show
you a quick and easy way to let BrowserHawk decide for you whether or not to use that
title attribute.
Here is an example of the title attribute. Since you are using IE4
or greater, if you hold your mouse over the following link for a few seconds, you will see
a tooltip, similar to the kind you see when you hold your mouse over a button on an
application's toolbar. This allows you to include a lot more information in a small space,
such as a navigation frame or a slim table cell.
Using two methods of BrowserHawk, we can quickly and easily check if
the visitor is using a browser which supports the title element (namely, that it is
Internet Explorer AND that it is version 4 or greater). Here is what the code looks like:
filename=/browserhawk/bhtitledetect.asp
<%
set bh = server.createobject("cyScape.browserObj")
if bh.version>=4 and bh.browser="IE" then
%>
<a href='x.asp' title=' This is the alternate text. '>
<% else %>
</a>
<a href='x.asp'>
<%
end if
set bh = nothing
%>
<p>
Hover here</a>
This logic could be used for any feature that you know is only
supported by certain browser versions. Sometimes it is worth it to prevent the waste of
bandwidth caused by adding elements and features to a page when they can't be viewed
anyway. But more likely then not, you'll use this approach to avoid inconsistencies with
layout and scripting across browsers.
Need a copy of BrowserHawk? See our section on Getting Started.
Copyright (c) 1999 cyScape, Inc.
All rights reserved. This material may not be published, distributed, or reprinted
without written consent from cyScape.
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