How to create a contact form with input validation?

Question

JavaScript

Good day! I am a beginner in programming, and therefore I ask for help, at least in which direction to move.
Task: to build a contact form module for Magento with validation of entered values ​​and their dependencies.
Question: I am building a regular contact form (First name, Last name, etc.), but with one peculiarity: there are fields card number and card code, it is necessary that when sending a request, the system checks the entered values ​​with an array of values ​​for numbers and codes, and it must be observed correspondence: each number corresponds to a certain code. If the number is correct, the code is correct, and they match, then everything is good otherwise an error.
Actually, in view of my poor experience in programming, I ask for tips in which direction to move, and how are such things implemented in general? Or for what queries to google?
Thanks to!

Answer 1

js form validation. Google it the same way ;) There are many options

Answer 2

Google form data validation, etc.

Answer 3

Everything is described in detail here, field validation classes and how to check the form itself (with the same classes), using ../js/prototype/validation.js you can (better rewrite it in skin) add your validation templates if necessary .