Popup Killer Test

Popup Killer Test
by
Mari Bontrager

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It's simple to test whether or not a browser is JavaScript enabled and to do appropriate actions:

<script language="Javascript"><!--
document.write('Yes! JavaScript!');
// --></script>
<noscript>
Your browser can't do JavaScript.
</noscript>

That's all you needed to do, back in the days when things were simpler. Now, with popup killers on so many surfer's machines, JavaScript enabled browsers won't necessarily launch your popups.

This can be frustrating if you use popups for help text, product descriptions, feedback forms, or other things deemed necessary for a complete appreciation of your site.

No more.

This article will show you how to check whether or not your visitor's browser allows popup windows.

This method has not been tested against all popup killers. So please, if you find it doesn't work for a certain browser/popup killer combination, tell us about it. You'll find contact links at the URL in the signature file of this article.

Here is how it works:

Your web page instructs the browser to make a popup. The code in this article demonstrates how to determine if it did or if it didn't succeed.

The Basic Code

The first thing to do is to put the following three blocks of JavaScript code into the HEAD area of your web page. It's important that the three blocks of code remain separate because at least one popup killer disables all JavaScript that's in the code block that would otherwise create a popup. So, with separate code blocks only one section is disabled and we can still use the rest of the code. It is also important that the three blocks of code are on your page in the same order as presented here. This will ensure that the first block of code is executed before the rest.

<script language="Javascript"><!--
TestString = 'failed';
// --></script>


<script language="Javascript"><!--
function InitializeTestPopup() {
TestPopup = window.open('','','height=100,width=100');
TestString = TestPopup;
TestPopup.close();
}
// --></script>


<script language="Javascript"><!--
function Verdict() {
if(TestString == 'failed' || TestString == null)
	{
	alert('No popup was made.');
	}
else
	{
	alert('Yes, browser does popups.');
	}
}
// --></script>

The first code block simply assigns a value to the variable: TestString

The second code block attempts to create a popup. If it succeeds, the variable TestString is assigned a complex number related to the popup's location in computer memory (once the value is assigned, the popup is automatically closed). If the popup does not succeed, the variable TestString will either be unchanged or it will be changed to null.

The third code block can be modified for certain actions (or inactions) depending on whether or not the browser will do popups:

Replace the
```
alert('No popup was made.');
```
line with what you want to happen when the browser will not make popups. You might change the message in the alert box (alert boxes should still be enabled even with popup killers) or replace the line with a document.write() to print a message on your web page, for examples. If you prefer that nothing gets done when popups are disabled, replace the line with two slashes: //
Replace the
```
alert('Yes, browser does popups.');
```
line with what you want to happen when the browser makes popups. You might replace the line with a popup launching function, for example. If you prefer that nothing gets done, replace the line with two slashes: //

Initializing the Test

The InitializeTestPopup() should be run when the page has loaded. (InitializeTestPopup() is in the second block of code in the HEAD area.) To do that, add an onLoad attribute to your BODY tag, like this:

<body onLoad="InitializeTestPopup()">

Using the Code

Here are two ways to use the code:

Automatic test completion.

If you want to conclude the test immediately and notify the user of the results, you can put the following somewhere in your page's BODY area.
```
<script language="Javascript"></script>
```
It is important that the browser has at least one second to create and destroy the test popup before you use the Verdict() function. Otherwise, you might get a false negative because the browser hasn't had time for the create/destroy cycle. That's why setTimeout() is used, with a delay of 1000 milliseconds.

The Verdict() function can be left as is if you simply want a test result message to be displayed. Otherwise, if you want to launch a popup automatically, for example, replace the
```
alert('No popup was made.');
```
and
```
alert('Yes, browser does popups.');
```
lines with your required action (or two slashes for inaction).
Complete test only when a link is clicked.

If you have help or definition links that create popups, you can do the test when the link is clicked. For example, let's assume your link was:
```
<a href="javascript:HelpPopup('Navigation')">
```
Then you would first change the link to:
```
<a href="javascript:Verdict()">
```
Then you would replace the
```
alert('No popup was made.');
```
line in the Verdict() function with:
```
alert('Sorry, popups must be enabled.');
```
and the
```
alert('Yes, browser does popups.');
```
line with:
```
HelpPopup('Navigation');
```

There are thousands of different popup implementations on the net. With the above code and consulting the examples, you should be able to adapt your pages quite nicely.

By: Will Bontrager

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