Auto-jump fields

Hi,

I need a user to input a code made of 4 parts of 3 alphanumeric characters each, for a total of 12 characters. It would look like this: 12A 3B6 9AD 4AF

To input that, I was thinking of using a form with 4 INPUT text fields, situated one beside each other in the page. From a constraints perspective, all fields should be required, and each input constrained to accept a minimum of 3 characters and a maximum of 3 characters.

I would like two things:

1. That the cursor “jumps” to the next field after the 3 characters are input without pressing Enter or tab or clicking on the next field.

2. That the field does not show the green tick mark when the field passed the validation.

I could not figure out how to do this…Is there a simple way to do it?

Many thanks in advance for the help,

Alex