UpdatePanel and Rendered (Inline) Javascript

It seems that the UpdatePanel essentially replaces the InnerHTML of  a DIV with the delta returned from the server. If you try this yourself you will notice that any javascript elements in the html are not fired.

All javascript registered on the server-side (if you are using .NET) with the ScriptManager is put into a separate section of the returned delta. The atlas runtime obviously then loads these scripts into the document manually.

What if the returned HTML has Javascript tags already rendered in it? Nothing. 😦
Such was our predicament and we had no control over the HTML that would be returned to the UpdatePanel (ReportViewer Control). Could we manually load the javascript ourselves when the UpdatePanel returns the payload? As it turns, we could.

You can create script elements on the fly and they get evaluated as you do. Atlas has the ScriptLoader object that will do it for you if your JavaScript is an external reference. Tweaking this idea we got a solution that found all the new Script elements and added them to the document.

The code is below; the scriptLoader was taken from this post.
The main thing to know is that a script element has a text property that can be modified.
The atlas scriptloader sets the src property whilst the innerHTML and innerText properties are readonly.

for(var n=0;n<control.children.length;n++){
if(control.children[n].tagName == ‘SCRIPT’){
}window.ScriptLoader =

new function(){varqueuedScripts = new Array();
varcurrentScript = null;functiononScriptLoaded(){
//Load next

//Add Support for error handlers
//Load next
doScriptLoad();} functiononScriptReadyStateChange(){
    if(event.srcElement.readyState == “complete” ||event.srcElement.readyState == “loaded”)
this.loadScript = function(scriptPath){
     if(currentScript == null)
//Does the actual script loading
if(currentScript){currentScript.onload = onScriptLoaded; //For Mozilla/Opera
currentScript.onerror = onScriptError; //For Mozilla/Opera
currentScript.onreadystatechange = onScriptReadyStateChange; //For IE

}if(queuedScripts.length == 0)
return;currentScript = document.createElement(“SCRIPT”);
currentScript.onload = onScriptLoaded; //For Mozilla/Opera
currentScript.onerror = onScriptError; //For Mozilla/Opera
currentScript.onreadystatechange = onScriptReadyStateChange; //For IE

currentScript.type = “text/javascript”;
currentScript.text = queuedScripts.pop();

In order to call ParseScript after an Asych postback we do the following. Now this was written when Ajax ASP.NET was stilled called Atlas so there is probably a better way these days, but it works for us 😉

function EndRequestHandler(sender, args)


9 Replies to “UpdatePanel and Rendered (Inline) Javascript”

  1. What would call the ParrseScript method on the client though? (and when?) What if some control nested inside the update panel is what triggered the asynchronous postback?

  2. I have edited the post to show how we do it. This solution was for a legacy custom control we could not modify. The page is focused around this control so every asych postback we want to run all inline scripts in the controls container (DIV).

    How you call ParseScript would depend on what you are trying to acheive. Generally you can modify custom controls to play nice with Ajax. If you can’t and our approach doesn’t work for you it’s possible to control when and where ParseScript runs from the server side.
    I.e. on postback test for asych, test the trigger control and add a javascript call to ParseScript if needed.

  3. Thanks
    this post helped me a lot
    I was trying to bind a handler to “readystatechange” with jQuery, but it doesn’t seem to work as I expected. you just saved me

  4. This is one of those things that make you jump with joy. Some guy built a rich page that uses a number of third party controls and now they ask us to make “partial postback” work on it – just like that. We managed to but the 3rd party control was spitting javascript that we had no way of adding to the page directly – until i saw this page. Great job and a big thank u.

  5. Hey, thank you for the post. I’m a begginer, so can you please tell me where should I copy this part:
    function EndRequestHandler(sender, args)

    Thanks for your time

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