JavaScript IE6 PNG Fix

In 2009 you’d think (and hope) that we could completely forget the problems with Internet Explorer 6. One of the issues that has caused me a lot of hassle is IE6s inability to render transparent PNG files correctly.

There are various ways to deal with IE5.5/IE6s PNG problem. I have tried several different ways of handling this situation – from using TwinHelix method, right through to serving alternative image content for IE5.5/IE6 via conditional comments and alternative stylesheets.

I’ve found the problem with the TwinHelix method is page load time is affected quite significantly, then serving alternative content via alternative stylesheets is a time-consuming way to handle this problem.

As I tend to use JavaScript to control various style elements that go above-and-beyond the capabilities of CSS alone, I have decided to use JavaScript to fix PNGs.

The limitation of this solution is that users who disable JavaScript will see the unfixed PNG images on their page if they are using IE5.5/IE6. However, in terms of caching and overall page speed, the small level of users browsing without JavaScript is something that I would balance in favour of a cacheable JavaScript solution to the problem.

I have been using the excellent DD_belatedPNG fix from Diller Design. All credits go to Diller Design, and to find out more please check out their site.

This easy to use method works in the following way:

1. Download the DD_belatedPNG JavaScript file (Right click > Save As). Uncompressed / Compressed. Check for latest version here.

2. Call the JavaScript file within the head section of your page as follows:

<script src="http://www.whatever.com/path/to/file/DD_belated_PNG_0.0.8a.js" type="text/javascript"></script>

3. Create a blank JavaScript file in Note Pad or an equivalent text editor and place the following code into the file, then save the file as pngfix.js:

DD_belatedPNG.fix('.png_bg');

4. In the above code replace .png_bg with any ID or class that you have applied to the image in your HTML code or in your external stylesheet. For example, if you want to apply the fix to your logo, you might give your image the class logo. This would look like the following:

<img src="http://path/to/image/file/logo.png" width="100" height="50" class="logo" />

5. If we carry on the example in step four, you would adjust the pngfix.js file as follows:

DD_belatedPNG.fix('.logo');

Other classes can be added by separating each class with a comma (I.e. DD_belatedPNG.fix(‘.logo, .icon, img’);).

6. Now call the pngfix.js file in the head of the page below the DD_belated_PNG_0.0.8a.js file as follows:

<script src="http://www.whatever.com/path/to/file/pngfix.js" type="text/javascript"></script>

7. In the head of the page you should have the following:

<script src="http://www.whatever.com/path/to/file/DD_belated_PNG_0.0.8a.js" type="text/javascript"></script>
<script src="http://www.whatever.com/path/to/file/pngfix.js" type="text/javascript"></script>

8. Now we want all other browsers to ignore the PNG fix, so we wrap the two JavaScript files in conditional comments as follows:

<!--[if lte IE 6]>
<script src="http://www.whatever.com/path/to/file/DD_belated_PNG_0.0.8a.js" type="text/javascript"></script>
<script src="http://www.whatever.com/path/to/file/pngfix.js" type="text/javascript"></script>
<![endif]--> 

Now if you test your page in IE6, you should find transparent PNGs that you have specified in the pngfix.js file are rendered correctly.

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Tags: Hacks, IE5.5, IE6, JavaScript, PNG Fix

Posted by Robin Parduez on Friday, 31st July 2009 at 14:29. You can follow any responses to this post by subscribing below the comment box. Comments are welcome.

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