no-throw.md

Disallow throwing exceptions (no-throw)

This rule disallows the throw keyword.

Rule Details

Exceptions are not part of functional programming.

throw new Error("Something went wrong."); // Unexpected throw, throwing exceptions is not functional.

As an alternative a function should return an error:

function divide(x: number, y: number): number | Error {
  return y === 0 ? new Error("Cannot divide by zero.") : x / y;
}

Or in the case of an async function, a rejected promise should be returned.

async function divide(x: Promise<number>, y: Promise<number>): Promise<number> {
  const [xv, yv] = await Promise.all([x, y]);

  return yv === 0
    ? Promise.reject(new Error("Cannot divide by zero."))
    : xv / yv;
}

Options

The rule does not accept any options.