This is a form I developed with Glenn Burnett at Zia based on a matrix he developed outlining the MSRB requirements for trade reporting.
Depending on whether it is a primary or secondary market transaction, involving varying combinations of syndicate managers, syndicate members, dealers or customers, along with two other questions that may or may not be relevant, the time period and specific rules vary.
This form walks you through the questions, and after each poses the next relevant question. Questions that aren't relevant to that particular type of transaction aren't shown. At the end, click the button and your requirement appears.
The javascript that generates this isn't particularly difficult, just tedious. The one trap I needed to avoid was when a user moved back a step; for example, changing a secondary transaction to a primary transaction. The onChange event for each pull-down menu clears all the values that follow it.
It's nice to be able to put some logic into this and be able to generate an answer without going back to the server.