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# no-callback-in-promise

[Added in v0.6.4](https://github.com/web-infra-dev/rslint/releases/tag/v0.6.4)
## Configuration

| Preset                              | Configured Value |
| ----------------------------------- | ---------------- |
| ✅ promisePlugin.configs.recommended | `"warn"`         |


```ts title=rslint.config.ts
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:

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

Examples of **correct** code:

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

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

## Options

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

### `exceptions`

An array of callback names to exclude from the check.

```js
/* 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`.

```js
/* 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.

## Original Documentation

- [eslint-plugin-promise: no-callback-in-promise](https://github.com/eslint-community/eslint-plugin-promise/blob/v7.3.0/docs/rules/no-callback-in-promise.md)
- [Source code](https://github.com/eslint-community/eslint-plugin-promise/blob/v7.3.0/rules/no-callback-in-promise.js)