Hi there,

I was just solving an issue with RegisterClientScriptBlock not working in Chrome and newer versions of Safari. I spent quite a time in searching Google to find just any useful information about this. The reason was that everyone is using different AJAX controls, so the same issue results in many different errors, including:

• Client side validators breaking the page on AJAX requests (it isn't them really, but if you remove them, you remove the AJAX code which breaks it)
• RegisterClientScriptBlock not working in update panels
• RegisterStartupScriptBlock not working in update panels
• Strange javascript errors in the browser like "ScriptManager is undefined" or "ToolkitScriptManager is undefined"
• etc.

Here is what I found out during my research and how I understand this issue happened:

I may be wrong but this is what I understood from various internet discussions and what lead me to the solution.

So here is the story:

What happened was that prior versions of Safari (WebKit based browsers) contained some bug that was breaking the AJAX functionality.

Then the good guys from Microsoft came and developed AJAX. While struggling with this Safari bug, they had to include some hack to their AJAX code to be able to work even with this bug. They anticipated that the bug will be around for quite a time so they hardcoded the fix to apply to all WebKit versions in the future.

But then the bad guys came (well, maybe they were also good, but in a different way), and fixed the bug in Safari, which resulted in bug in already existing code of AJAX which is still applying the hack to fix it.

How to solve it?

Well it is quite simple, but no one would ever anticipate it. You need to convince the browser that it is not a browser with this bug that needs to be workarounded, but that it is some completely different browser. Here is how you do it, just add following javascript code to your page:

if (typeof(Sys.Browser.WebKit) == "undefined") {
  Sys.Browser.WebKit = {};
}
if (navigator.userAgent.indexOf("WebKit/") > -1) {
  Sys.Browser.agent = Sys.Browser.WebKit;
  Sys.Browser.version = parseFloat(navigator.userAgent.match(/WebKit\/(\d+(\.\d+)?)/)[1]);
  Sys.Browser.name = "WebKit";
}

This makes sure that the AJAX fix to the WebKit browsers won't apply and it will allow your AJAX code work.

Neat, isn't it?

My thanks belong mainly to following two sources:

http://blog.lavablast.com/post/2008/10/20/Gotcha-WebKit-(Safari-3-and-Google-Chrome)-Bug-with-ASPNET-AJAX.aspx
http://stackoverflow.com/questions/508994/asp-net-dropdownlist-autopostback-and-google-chrome

Now I can find much more sources regarding the same issue because I know what we are dealing with exactly, but as I said, it is very hard to find something initially, without prior knowledge, you just don't know what to look for ...

And also note, that with Kentico CMS 5.0, this issue will be fixed automatically.

See you next time