Then closing it, as there are two open issues about javascript below.

If it's javascript, duplicate issue. If it's not, mention the language.

Hi, thx!

done

In general, the Date Of Birth field does not have to be in date format, the only condition is that it is a string equal to 16 characters!
But thanks for the improvements you suggested!
I applied random date generation which you and mamamia5x suggested

Is there a chance that Feb 29th occurs in [code] ?

There is, but small. But in your 'manual' implementation it's just the same. If author wants to target specifically leap years with random tests, they need to tune the generator to ensure generation of such dates:

it("Leap years", () => {

  let date = new Date(2000 + random(5) * 4, 1, 29).toISOString().slice(0, 10); // luckily, year 2000 was a leap year
  ...
});

or something, depending on what exactly is needed.

Can't you just do Date(year:2000).add(days: random(20*365)).format('yyyy-MM-dd') in Javascript?
Handling calendars maually is asking for trouble.

let date = new Date(2000, 0, Math.random() * 20 * 365 + 1 | 0).toISOString().slice(0, 10);

Good idea, thanks! In addition to the current description, I will add an image with a grid showing how the information will be displayed in the result