Form Error Trapping

I have a form that I need to add some advanced error trapping to. I need to this to make sure the form is filled out properly.
I would like to be pointed in the right direction on how to get started since it is rather complicated.
So here is what I have. I have 1 check box:

<input name="accrued_annual_leave" type="checkbox" value="AL">

And I have 5 inputs. They are:

<input class="date_entry_area" name="accrued_al_date_from" type="text" maxlength="10">
<input class="date_entry_area" name="accrued_al_date_to" type="text" maxlength="10">
<input class="time_entry_area" name="accrued_al_time_from" type="text" maxlength="5">
<input class="time_entry_area" name="accrued_al_time_to" type="text" maxlength="5">
<input class="total_entry_area" name="accrued_al_total_hours" type="text" maxlength="3">

What I want to do is the following. When trying to submit, if "AL" is checked, for it to check to make sure all 5 inputs have values inside. Then, for it to focus to the one that is empty. And so forth.

Then, if information is entered into any of those 5 inputs, for "AL" value to be changed to checked.

Any ideas?

Hi

I have similar principals explained here > http://javascript.internet.com/forms/

I'd suggest using a server-side script for validating post data, it is much more secure.

I think he means he just wants some simple validating doing BEFORE submission.. using, for example, onChange= in the text fields.

IE: <input name="sd1" type="text" id="sd1" size="6" onChange="docalcs()">

That way, it is even more secure because it isn't travelling backwards and forwards with error messages. And the form only needs to be submitted once.

Cool. Found several good pieces of code in the page you suggested.