Today I was testing a website using a HTML W3C validation tool (XHTML 1.0 Transitional) and I found a problem in my links. Some URLs had the & symbol, since they linked to dynamic webpages which need parameters. The trivial solution is to replace the “&” occurrences on all links by the equivalent “&” expression. But while changing some dynamically generated URLs I found out an interesting fact about ASP.NET controls vs HTML controls that I was not aware of.
In the example bellow you can see 2 pairs of Links and Images. The first set are ASP.NET controls, the second one are HTML controls (markup) with runat attribute set to server in order to allow their manipulation by ASP.NET code.
When you look at the source code in the client side bellow you can spot a slight difference that can make your HTML validation fail. href and src attributes that originally contained the “&” and which are the result of ASP.NET controls rendering have “&” instead, but the HTML controls still have the invalid &-based URL’s.
Since I had both type of elements mixed in the website, and I was threating them in the same way I was getting different behaviors. Now I know why…
