Why is an empty required field coming from a form?

Question

Web development

Greetings.
There are at least 2 required fields in the quiz form on the site.
Without the order urgency field, it is impossible to fail to the next stage and the phone number, without which the application is not sent.
Today I received two empty letters.


I don't think it will work with my hands.
Intercept? Substitute? Site on https.
The form is here - https://quiz.nikolaspotolki.ru/
If anyone wants to test, give the type number 111111111, please.

Answer 1

You can’t rely on client-side checks, firstly, of course, before sending data, you should try to check with the script that all fields are filled in (this does not guarantee anything, but it excludes accidental form submission or simple data substitution), and secondly, on the server, be sure to check the availability of the required data format, and if they do not match, do not send anything anywhere, but send an error like "required fields not filled" to the front.
The main rule of a web developer - by default, everything that comes from the client is crap, mura and hacking attempt, until proven otherwise.