javascript problem: what am I missing?

TheDoug · Apr 24, 2007

The basic goal here is to switch randomly between two banner ads sourced from individual javascripts, inserting them in the <p> tag in the body of the document. At this point I can't tell if the problem is with the code, or with the fact it just may not like calling the .js files. Any assistance would be most appreciated.

Code:

<html>
<head>
<script type="text/javascript">
      
                window.onload = function() {
                        var adBlock = document.getElementById("adBlock");
                        var scriptTag = document.createElement("script");
                        scriptTag.type = "text/javascript";
                
                        if (Math.round(Math.random()) == 0) {
                                scriptTag.src = "http://www.my1domain.com/ad1.js";
                        } else {
                                scriptTag.src = "http://www.my2domain.com/ad2.js";
                        }
                
                        adBlock.appendChild(scriptTag);
                }
        </script>

</head>
<body>
<p id="adBlock" align=center></p>
</body>
</html>

matt.chugg · Apr 30, 2007

There are lots of different ways you can accomplish this.

heres how I would do it
Code:
	banners = new Array(2);

	banners[0] = "<img src='http://www.my1domain.com/ad1.js'>";
	banners[1] = "<img src='http://www.my2domain.com/ad2.js'>";

	index = Math.floor(Math.random() * banners.length);

	document.write(banners[index]);
or in less lines
Code:
	banners = new Array(2);

	banners[0] = "<img src='http://www.my1domain.com/ad1.js'>";
	banners[1] = "<img src='http://www.my2domain.com/ad2.js'>";

	document.write(banners[Math.floor(Math.random() * banners.length)]);
This way you can just add new banner lines and not have to change any numbers since the random function is between 0 and the size of the array.

TheDoug · Apr 30, 2007

Excellent. Thanks. With only minor modification ('script src=' instead of 'img src='), and moving the document.write to the spot where I want the ad, it looks like it's behaving exactly as desired.

Edit: Spoke too soon. Works in Moz/FF, not IE.

TheDoug · May 2, 2007

Got it figured out:
Code:
var banners = new Array(2);

banners[0] = "<script src='http://www.my1domain.com/ad1.js'><\/script>";
banners[1] = "<script src='http://www.my2domain.com/ad2.js'><\/script>";

index = Math.floor(Math.random() * banners.length);

document.write(banners[index]);
Needed closing <\/script> tags for IE to properly handle the called scripts. It's always fun when technically "broken" code works in some browsers.

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javascript problem: what am I missing?

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