Select controls and empty values

Javascript problems

[Reflection]

Ok first I will describe what I am trying to accomplish:

I have 3 form controls. The first(A) is a select drop down. The second(B) is another select, which is disabled until the first has a value. The third(C) is a text box which is disabled until the first 2 selects have a value.

A is the number of weeks, B is a start date, and C is an end date.

The idea is that the user selects a value in A which causees B to be populated with values and enabled. The user then selects a value in B which causes a text value to be displayed in C.

Make sense? :)

The problem I have is that initialy I would like the selects to be 'blank' meaning the first 'option' in the select control wont have any text. This is easy enough to do but it becomes a problem because it leaves open the posiblity that the user can re-select the 'blank' option, which of course screws up the javascript that calculates the value to be displayed in C.

Hopefully that makes my problem clear, its a little long winded ;)

Any help would be appreciated.

Thanks

[Purple Martin]

How about using a validation function called by the onChange event. If the user changes it to blank, give them a friendly alert message and put the focus back in the blank control.

[MonkeeSage]

You can also set the blank to the same value as the first option, just don't show any text in it...

<option value="1" selected></option>

Jordan

[stevenjm]

Only just learning javascript but can't you put an "if" in the appropriate place in your code to detect a nul value and an alert box.

[Reflection]

Thanks guys. Alert boxes arent an option as they are confusing/annoying for the user I will see how MonkeeSage's method works out.