Calling Javascript function from C# event in ASP.NET

Question

This is in ASP.NET with C#. I am trying to programmatically call a Javascript function from a radiobuttonlist click event. I have created the radiobuttonlist and added a couple of list items inside. I have looked around a lot but have been unable to figure this out.

C# code:

RadioButtonList _rbList = new RadioButtonList();
_rbList.ID = r[0].ToString()+"Answer";
_rbList.RepeatDirection = RepeatDirection.Horizontal;
_rbList.Attributes.Add("onchange", "return answered();");

Javascript inside my .aspx:

<script type ="text/javascript">
function answered() {
    alert("I am an alert box!");
}
</script>

When you say you're trying to call a javascript function from your C# event handler, do you mean you're trying to wire up a javascript event, or you actually want to run some javascript code when the page renders? — Gromer
– Gromer, Commented Oct 16, 2012 at 21:46
You do know that using pure javascript and html (not using websockets or any other server-client push technology) that you can't have the server cause the client to do some random action, right? The client has to initiate all requests, or you have to setup some sort of a trigger (timer?) to operate for you. — jcolebrand
– jcolebrand, Commented Oct 16, 2012 at 21:46
Forgive me, but isn't C# the server side language? I suppose you could use DWR to remote control the browser to a point...directwebremoting.org/dwr/index.html — Andrew Rhyne
– Andrew Rhyne, Commented Oct 16, 2012 at 21:46
As for wiring up the javascript to run on the change event, it might be easier to use the OnClientChange event, yes? — jcolebrand
– jcolebrand, Commented Oct 16, 2012 at 21:47
If you do just want to inject some javascript to run, check out this Q/A: stackoverflow.com/questions/666519/… — Gromer
– Gromer, Commented Oct 16, 2012 at 21:47

RollRoll · Accepted Answer · 2012-10-16 22:18:42Z

2

You adding the onchange on the RadioButtonList...

Add it to the RadioButton inside of RadioButtonList and it will work, which in lower level speaking, adding attribute to the ListItem from Items from RadioButtonList, just one problem...

adding "onchange" attribute will be render a <span> containing the <input radio, pretty gross I know, try to add onclick instead, so the render can attach the attribute to the <input radio ,and do your magic on the javascript click, something like that:

RadioButtonList1.Items[0].Attributes.Add("onclick", "return answered();");

edited Oct 16, 2012 at 22:18

answered Oct 16, 2012 at 21:49

RollRoll

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1 Comment

jcolebrand Over a year ago

I was just looking this up, there's no OnClick or the like handlers for the RBL in MSDN: msdn.microsoft.com/en-us/library/ads2w011.aspx

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