Our next example shows you how to detect a particular
browser. As mentioned earlier, this is useful because you could have a
page that supports JavaScript for only Netscape 3.0, therefore, you don't
want a visitor to visit the page without that browser.
Detecting the appropriate browser
<HTML>
<TITLE>Detecting User's Browser</TITLE>
<HEAD></HEAD>
<BODY BGCOLOR=ffffff>
<SCRIPT Language="JavaScript">
if (navigator.appName == "Netscape"){
if (navigator.appVersion.substring(0, 3) == "3.0"){
if (navigator.appVersion.substring(3, 4) == "b"){
alert('You are using :' + navigator.appName + ' (' +
navigator.appCodeName + ') ' + navigator.appVersion +
'\nSorry! You are not using Netscape 3.0+');
history.back();
}
}
}
else {
alert('Sorry! You are not using Netscape 3.0+');
}
</SCRIPT>
</BODY>
</HTML>
Here we use the some of the properties of the Navigator object.
First we find out if the browser is a Netscape browser. If so, we detect
if the version is 3.0. If the version is a beta version, we display
the whole browser information with its platform, and alert the user
that he or she is not using a Netscape 3.0 browser.
Notice that before we closed the if statement, we used
the history.back() statement. It is used so that when the
user presses OK on the alert message box, the document automatically
takes the user to the previous page. This is useful because sometimes
if you run JavaScript 1.1 on Netscape browser 2.0 or earlier, the browser
might crash; this will prevent users from crashing their browsers.
Here's another useful tip: You can send the user to a different
page if the browser isn't Version 3.0. Instead of the history.back()
statement, you need to type the following statement: window.location="myotherpage.html".
This script can also alert visitors that if they want to view this
page, they need to acquire the appropriate browser.
Alert:
The else statement is not effective unless you use a JavaScript-enabled
browser besides Netscape, such as Microsoft's Explorer 3.0.
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