At least one

From: 4 Unwritten Rules for Writing Code I Barely See Anyone Mentioning | JavaScript in Plain English

These rules separate bad developers from great ones

1. Only comment what your code can’t express
2. Don’t make a massive change to the codebase
3. Don’t use confusing names in your codebase
4. Keep the function length small

Well, at least the fourth is one of the staple suggestions of the GNU guidelines.