Settings "auto-fill" on creating new item

When creating a new item, I would like some fields to be automatically generated/filled, according to my preferences:

  1. Email: Generate sub-addressing, using [email protected]
  2. Password: Generate using these options …
  3. Add boolean custom field: name=“Random”, value=true.

And ideally:

  1. Name: Use my custom JavaScript function (input=URL<>, output=Foo-Bar => not always perfect but closer than URL).

These values should be filled also if no value is provided. Actually, “email” and “password” should be generated only if not initial value provided. And “name” should always be executed.

In the rare cases it won’t be what I want, I can change the value or empty/delete them.