I have an unknown number of textboxes on my form. They will be called person(i) so if I have 3 textboxes I will have person1, person2, and person3. I want to be able to create a for loop that will loop through each one of these controls...
You just about never need to use eval; the only time I've ever seen to prove useful is to avoid scoping issues, but that isn't the case in this instance. You need to recall that the form object has an elements array in which it's child elements can be accessed though. It could be as simple as this:
for(i=0 i<theForm.elements.length; i++) theForm.elements['element' + i ].value = 'This is element ' + i + '.';