Reference textbox in newthread/newreply

[mathforum]

I am trying to use javascript to render something within the newthread or newreply textbook if it fits certain conditions. The latter part is already coded and isn't the problem (not yet at least). What I need to do is be able to give an element for the javascript function to check and then act on. How can I reference all text within these textboxes?

If that's too vague, what I need to do is label the textarea with this line:

<input id="MathInput" size="80" onchange="UpdateMath(this.value)" />

That id and update loop are both needed for the javascript to input text to work with. Any ideas?