Eslint combining naming conventions

Question

I want to combine snake_case and PascalCase naming conventions. So, declaring a class its name must match the following format strictly: Pascal_Snake, Pascal_Snake_Pascal_Etc, OnlyPascal, Pascal.

That's what I'm trying to do in my esling.config:

"@typescript-eslint/naming-convention": [
  {
      selector: "class",
      format: null,
      custom: {
          regex: "([A-Z]\\w*_?[A-Z]\\w+)|([A-Z]\\w*[A-Z]?\\w+)",
          match: true,
      },
  },
]

Unfortunately, this regex is not strict. What I want is:

1. After _ there must be at least one capital letter always.
2. If you do not provide _ — you must name classes according to PascalCase format.

How to get it?

Answer 1

Using \w can match upper/lower case chars and _

You could match an optional underscore before matching an uppercase char A-Z in an optionally repeated group.

(Note to double escape the backslashes if that is required.)

\b[A-Z][a-z]*(?:_?[A-Z][a-z]*)*\b

Regex demo

If you don't want to match a single A or AA, you can repeat the lowercase chars 1+ times instead.

\b[A-Z][a-z]+(?:_?[A-Z][a-z]+)*\b