#promise/no-callback-in-promise

#Configuration

import { defineConfig, promisePlugin } from '@rslint/core';

export default defineConfig([
  promisePlugin.configs.recommended,
  {
    rules: {
      'promise/no-callback-in-promise': 'error',
    },
  },
]);

Disallow calling cb() inside of a then() (use util.callbackify instead).

Mixing promise callbacks (.then / .catch) with Node.js-style error-first callbacks (cb, callback, next, done) makes control flow harder to reason about and is a common source of swallowed errors. This rule flags places where a callback is called or passed inside a promise handler.

#Rule Details

Examples of incorrect code:

a.then(cb)
a.then(() => cb())
a.then(function(err) { cb(err) })
a.catch(function(err) { callback(err) })

Examples of correct code:

// callback outside a promise — fine
function thing(cb) { cb() }

// wrapped in a timeout (default: timeoutsErr is false)
whatever.then((err) => { process.nextTick(() => cb()) })

#Options

{
  "promise/no-callback-in-promise": ["warn", {
    "exceptions": [],
    "timeoutsErr": false
  }]
}

#exceptions

An array of callback names to exclude from the check.

/* eslint promise/no-callback-in-promise: ["warn", { "exceptions": ["next"] }] */
a.then(() => next())  // OK — "next" is excluded

#timeoutsErr

When true, passing or calling a callback inside setTimeout, setImmediate, requestAnimationFrame, or process.nextTick that is itself inside a promise handler is also an error. Defaults to false.

/* eslint promise/no-callback-in-promise: ["warn", { "timeoutsErr": true }] */
whatever.then(() => { process.nextTick(() => cb()) })  // error
whatever.then(() => process.nextTick(cb))              // error

#Differences from ESLint

None. The rule behaves identically to the upstream eslint-plugin-promise implementation.