quick-lint-js

Find bugs in JavaScript programs.

E0241: newline is not allowed between field name and '!'

In TypeScript, ! after a field name indicates a definite assignment assertion. It is a syntax error to put the field name on a different line from !:

class Banana {
  skin
    !: BananaSkin | undefined;

  peel() {
    this.skin = undefined;
  }
}

To fix this error, put ! immediately after the field name, on the same line:

class Banana {
  skin!: BananaSkin | undefined;

  peel() {
    this.skin = undefined;
  }
}

Documentation for other errors