asp.net GetElementByid().value element/property not available

Question

Here's another one that's got me ripping what's left of my hair out.

My latest asp.net page is something I just threw together for an in-house database tool. It uses the standard VS 2010 design template, which means it uses the site.master page. I mention this because it may be relevant to my problem.

I'm using asp:textbox controls instead of input type="text". When one textbox 'blurs,' I need to run a sub in code-behind that will do a database lookup based on the information typed in the textbox.

Everything I see about this is that I need to add a asp:hiddenfield to trigger the code-behind event to do the lookup. So I use document.GetElementById method in a JavaScript script to set the value in the hidden field. What it's supposed to do is: document.GetElementById('HiddenInfo').value = "yada-yada".

My problem is that the VS development environment doesn't recognize the .value property for GetElelmentById command. For example, as is its wont, VS will give code hints as you type. When I get to where I want to insert the .value parameter, it doesn't show up on the list of suggestions. See illustration:

enter image description here

As you can see, typing the v doesn't bring up the .value parameter.

I've tried getting it by ClientID and by using jquery, and nothing works. The crazy thing is that I have done this before with anther web page I developed, but the only difference is that one did not have a site.master page.

I've spent hours trying to find the answer online, and nothing is quite exactly the same as my problem.

Any ideas?

Thanks!

it will not always show up in intellesense, but that doesn't mean it won't work. — attila, May 05 '14 at 22:05
Has same problem. Refer to this link http://stackoverflow.com/questions/9101904/document-getelementbyidid-value-failing-in-asp-net-javascript-function — Syed Ali Taqi, May 15 '14 at 06:29

score 0 · Answer 1 · answered May 05 '14 at 22:55

0

Well that's an asp .net element, so your going to have to get its clientid I believe. Here it is in jquery:

$('#<%=HiddenInfo.ClientID %>').val();

answered May 05 '14 at 22:55

mgmedick

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7
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I had tried that, except I didn't put the hash tag at the beginning. – Bill Norman May 05 '14 at 23:19
(the hash tag would be jquery-specific.) – wazz May 06 '14 at 08:58

score 0 · Accepted Answer · answered May 07 '14 at 15:31

Hours and hours later, I finally found the answer. In the JavaScript function that changes the value of the HiddenInfo field, one line is added that (I guess) forces a postback, which then fires the _ValueChanged event in code behind:

<script language="javascript" type="text/javascript">
function CheckCC() {
    document.getElementById('HiddenInfo').value="YES";
    <%= ClientScript.GetPostBackEventReference(HiddenInfo, "") %>;
}

I dug up the answer here.

Seems like a pretty obscure solution.

The odd thing is that in a previous asp.net design of mine, this wasn't necessary. That's what was really confusing me, and I still don't understand it. But at least I can move forward now.

Thanks everyone for your suggestions.

asp.net GetElementByid().value element/property not available

2 Answers2