Problems with ASP.Net object and Javascript

[tshad]

I am trying to set some labels to display calculated values with posting
back to the server. So I am using Javascript to set the values of my
asp:label. The problem is that an asp:lavel renders into a span element.

For example:

function SalaryDisplay(me)
{
var salaryMinLabel = document.getElementById("SalaryMin");
salaryMinLabel.value = 200;
alert("after setting salaryMinLabel = " + salaryMinLabel.value);
}

The asp.net object:

<asp:label id="SalaryMin" runat="server" />

Which renders into:

<span id="SalaryMin"></span>

The function seems to find the span fine. The alert box shows that it is
set to 200. But the web page never shows it.

There seemed to be a problem with the span element.

Then I found out that the 'value' property on span does not display. The
newly-created span element
is empty and needs to have a text node appended. So to create the node I do
the following:

var salaryMinLabel = document.getElementById("SalaryMin");
var sMLText = document.createTextNode("200")
salaryMinLabel.appendChild(sMLText);
alert("after setting salaryMinLabel = " +
salaryMinLabel.firstChild.nodeValue);

Even though it displays on the page the viewsource displays:

&nbsp;&nbsp;Yearly Compens:<span id="SalaryMin"></span>&nbsp;/&nbsp;
<span id="SalaryMax"></span>

The value is not there.

This obviously is not going to work. I spent a lot of time getting this
work correctly and just found that if you go back a page (or forward) and
then go back to the page - all this SPAN information that was just generated
is now gone. Probably related to why it doesn't appear in Viewsource even
though it is displaying on the original page.

Is there a way to make sure it stays with the page on repost?

Thanks,

Tom

 

[Marina]

First off, anything you change in javascript isn't going to be visible in
View Source. That just shows the page exactly as it came down from the
server.

Try setting the innerText or innerHTML properties of the span. The 'value'
property is good for input controls, i don't think it works for spans.

 

[Guest]

Stick with innerHTML as it's in the W3C standard.

innerText is only support by Internet Explorer.

 

[tshad]

Stick with innerHTML as it's in the W3C standard.

How do you set this in Javascript and does it carry over to the asp.net
page?

Does that mean I don't need to add a node as I have been doing?

Thanks,

Tom

 

[Guest]

How do you set this in Javascript and does it carry over to the asp.net

page?

Nope, once it gets back to the server the value will be blank again. If you
want to keep the value once you've posted back to the server, you'll need to
put it into some type of input field, for example a HtmlInputHidden (<input
type="hidden" id="blah" name="blah">). If you don't mark the hidden input
field as runat="server", you'll still be able to access the value via
Request.Form["blah"] (in C#, not sure what VB syntax is).

To set the value via Javascript, it should be just:

var salaryMinLabel = document.getElementById("SalaryMin");
salaryMinLabel.innerHTML = '200';

If you want to set it to a hidden input field (i.e. so it's persisted when
you post-back), it should be just

var salaryMinHidden = document.getElementById("SalaryMinHidden");
salaryMinHidden.value = '200';

Does that mean I don't need to add a node as I have been doing?

Yes, you shouldn't need to add a node.

HTH -
/gerrod