how to parse changes to control attributes by javascript at post back

[Jeremy Chapman]

I've created a custom control which outputs html at runtime like <span
id="controlid" value="myvalue"></span>. On my page I have javascript that
changes the value of the value attribute. On post back I want to parse the
html changed by the javascript and update a server side variable. I thought
this could be done in by the adding IPostBackDataHander interface to my
classes inheritance, and adding the IPostBackDataHandler.LoadPostData to my
class, and in the OnPreRender of my control calling
Page.RegisterRequiresPostBack(this);. My LoadPostData method gets called on
the postback but I still cant seem to get the new value of the value
attribute from the NameValueCollection. What am I doing wrong?

 

[Raymond]

The span element isn't a form field.
Add the value to a hidden form field besides span.

 

[Jeremy Chapman]

Ok, thanks. that works. What controls are considered form fields?

 

[Raymond]

The various input types, textarea, and select.
The html button type, may be, may be not, best not
use that one as a form field.