Show off your HTML/Javascript cleverness

[Dave Cross]

I need some HTML/Javascript help.

See http://dave.org.uk/grid.html.

On this page you have a list of courses (Course 1 to Course 6) and three 
time periods (T1 to T3). The idea is that each person will select one 
course for each of the three time periods.

I have it set up so that each time period has a set of radio buttons 
associated with it (one for each course). This ensures that each person 
can select only one course per time period. But it doesn't stop them 
from selecting the same course for all three time periods - which I 
don't want to allow.

Then there's course 6. Course 6 runs across all time periods. If you 
select course 6 then you can't select any more courses.

I guess I need to write some Javascript that enforces these extra 
rules[1]. But I thought that the clever people in london.pm might have 
some clever ideas. So I'm asking you first.

How would you implement this?

Dave...

[1] And, yes, I know I'd need to implement the same checks server-side 
as well.

-- 
Dave Cross :: dave at dave.org.uk
http://dave.org.uk/
@davorg