#no-promise-in-callback

#Configuration

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

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

Disallow using promises inside callbacks.

#Rule Details

Promises and callbacks are different ways to handle asynchronous code. Mixing the styles inside the same callback can make error handling unclear: callback errors are usually passed through the callback argument, while promise errors must be handled through the promise chain.

This rule reports promise-like calls inside callback-like functions whose first parameter is named err or error.

Examples of incorrect code for this rule:

doSomething((err, value) => {
  if (err) {
    console.error(err)
  } else {
    doSomethingElse(value).then(console.log)
  }
})

function handler(err) {
  Promise.resolve(err)
}

Examples of correct code for this rule:

promisify(doSomething)()
  .then(doSomethingElse)
  .then(console.log)
  .catch(console.error)

doSomething((err, value) => {
  return doSomethingElse(value).then(console.log)
})

Promise callbacks passed to .then() or .catch() are not treated as callback containers for this rule.

#Options

#exemptDeclarations

Pass { "exemptDeclarations": true } to exempt function declarations. Defaults to false.

{ "promise/no-promise-in-callback": ["warn", { "exemptDeclarations": true }] }

With this option enabled, this code is valid:

function handler(err) {
  Promise.resolve(err)
}

Function expressions and arrow functions are still checked when this option is enabled.

#Differences from ESLint

None known.

#Original Documentation

• eslint-plugin-promise: no-promise-in-callback