Dirty Tricks for Dirty Problems
Normally, with access to a server side language, this would be easy to implement. In .NET it could be checked with a single line of code using the System.IO.File class and its static Exists method.
However, in my case, the path to the image was generated by a tool and I couldn't modify it. All I had access to was the client HTML for the image, but I always got back a full image path to the product's image, whether it existed or not. The code just assumed that there would always be an image available named after its product ID (e.g. 12345.jpg).
I could of course create "No image available" images for all the missing images, but that would have meant a lot of work. Besides, it wasn't future-proof as it was quite likely new products without images would pop up in the system.
Then I remembered a little client side trick using the onerror attribute. All I needed to do was change the src attribute of the image in its onerror handler, like this:
<img src="http://imar.spaanjaars.com/DoesNotExist.jpg" onerror="this.onerror=null; this.src='http://imar.spaanjaars.com/DoesExist.jpg';" />
When the image cannot be loaded successfully, the img element fires its onerror event. Inside the (in-line) handler for that event, a new image is loaded that does exist.
Simple, and easy to implement. Note that this solution may not work in all browsers, as it's currently not standards compliant. It looks like it's going to be added to HTML 5 though (warning: this is a huge document).
Where to Next?
Wonder where to go next? You can post a comment on this article.
Links in this Document
Talk Back! Comment on Imar.Spaanjaars.Com
I am interested in what you have to say about this article. Feel free to post any comments, remarks or questions you may have about this article. The Talk Back feature is not meant for technical questions that are not directly related to this article. So, a post like "Hey, can you tell me how I can upload files to a MySQL database in PHP?" is likely to be removed. Also spam and unrealistic job offers will be deleted immediately.
When you post a comment, you have to provide your name and the comment. Your e-mail address is optional and you only need to provide it if you want me to contact you. It will not be displayed along with your comment. I got sick and tired of the comment spam I was receiving, so I have protected this page with a simple calculation exercise. This means that if you want to leave a comment, you'll need to complete the calculation before you hit the Post Comment button.
If you want to object to a comment made by another visitor, be sure to contact me and I'll look into it ASAP. Don't forget to mention the page link, or the Doc ID of the document.
Please correct the following errors:
Unfortunately, something went wrong and your message or comments have not been submitted successfully.
There's a fair chance things broke down because you tried to post something that looks like HTML. Things that look like HTML include (X)HTML, obviously, XML, ASP.NET markup and c# generics syntax as all of them use the < and > characters.
If that's the case, try altering your message and remove anything that looks like an angled bracket. You can replace them with [ and ] for example so you can still make it look like HTML to some extend.
If, on the other hand, you were trying to spam this web site, I am pretty glad I caught you in the act and stopped you from doing so ;-)
Also, please don't use links in your posts; I had to block them to filter out most of the junk mail I am receiving.