Text Box Not Defined?

I posted this in a JS forum, but to no responses, I put out a plea to the JSP Gods:

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I have a javascript function to check the validity of the contents of a couple-o-textboxes.

BUT --> I am using a JSP that may or may not actually have displayed said textboxes.

Is there a way in Javascript to check if the textbox is defined?

I get an telephone_contact not defined error and wish to check for the definition of telephone_contact and patient_contact before checking validity

[571 byte] By [wmacey] at [2007-9-26 1:51:39]