no-throw-literal

JavaScript lets you throw any value, but code that catches it expects an Error. A thrown string has no stack trace, so you can't see where it came from. error.message is undefined on it, and error instanceof Error is false.

The rule only looks at the syntax. It reports anything that can never be an Error: strings, numbers, null, undefined, object literals, template literals, and strings built with +. A variable, a property or a call's result could hold an Error, so those are allowed. @typescript-eslint/only-throw-error checks their types.

Configure

Off by default. To turn it on:

[lint.rules]
"no-throw-literal" = "error" # or "warn"

Examples

Reported:

function find(id) {
  if (!id) throw "id is required";
  if (id < 0) throw { code: 400 };
  if (id > max) throw "no such id: " + id;
  throw undefined;
}

Not reported:

function find(id) {
  if (!id) throw new Error("id is required");
  if (id > max) throw new RangeError(`no such id: ${id}`);

  const error = new Error("bad request");
  error.code = 400;
  throw error;
}