no-promise-executor-return

Disallow returning a value from the function passed to new Promise

has suggestions

new Promise ignores whatever its function returns. A return value there usually means you meant resolve(value), and the promise never settles.

An arrow function without braces also returns a value. For example, resolve => setTimeout(resolve, 100) returns the timer. That one's harmless, but it's reported too. Put the body in braces.

A return without a value is allowed, so you can still leave the function early.

Configure#

Off by default. To turn it on:

bunfig.toml
[lint.rules]
"no-promise-executor-return" = "error" # or "warn"

Every option, set to its default:

bunfig.toml
[lint.rules]
"no-promise-executor-return" = ["error", {
  allowVoid = false,
}]

Examples#

example.js2 problems
function readCached(key) {
  return new Promise((resolve, reject) => {
    if (cache.has(key)) {
      return cache.get(key);
    }
    load(key, resolve, reject);
  });
}

const wait = ms => new Promise(resolve => setTimeout(resolve, ms));
example.jsNo problems
function readCached(key) {
  return new Promise((resolve, reject) => {
    if (cache.has(key)) {
      resolve(cache.get(key));
      return;
    }
    load(key, resolve, reject);
  });
}

const wait = ms =>
  new Promise(resolve => {
    setTimeout(resolve, ms);
  });

Options#

OptionDefaultWhat it does
allowVoidfalseAllow returning a void expression, which says you're dropping the value on purpose.

With { allowVoid: true }, this is allowed:

example.jswith { "allowVoid": true }No problems
const wait = ms => new Promise(resolve => void setTimeout(resolve, ms));

Without the option, that line is reported:

example.js1 problem
const wait = ms => new Promise(resolve => void setTimeout(resolve, ms));