Where can I read how to prefill form fields?

Question

PHP

Good afternoon.
Plz tell me where you can read how to pre-fill / auto-fill the form.
This means not just the initial filling out of the form with the help of value, but it is necessary that when you enter the phone, the "+" sign is already there, you write 7 and the cursor is thrown into brackets, after entering three digits it is thrown from the brackets further.

Answer 1

Ready plugins
https://github.com/RobinHerbots/jquery.inputmask
digitalbush.com/projects/masked-input-plugin
We change value on change/input/keyup event. What can be written there?

Answer 2

Input Mask....
https://plugins.jquery.com/tag/mask/