# eslint-plugin-promise Enforce best practices for JavaScript promises. [![travis-ci](https://travis-ci.org/xjamundx/eslint-plugin-promise.svg)](https://travis-ci.org/xjamundx/eslint-plugin-promise) [![npm version](https://badge.fury.io/js/eslint-plugin-promise.svg)](https://www.npmjs.com/package/eslint-plugin-promise) [![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg)](https://github.com/prettier/prettier) <!-- START doctoc generated TOC please keep comment here to allow auto update --> <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE --> - [Installation](#installation) - [Usage](#usage) - [Rules](#rules) - [Maintainers](#maintainers) - [License](#license) <!-- END doctoc generated TOC please keep comment here to allow auto update --> ## Installation You'll first need to install [ESLint](http://eslint.org): ``` $ npm install eslint --save-dev ``` Next, install `eslint-plugin-promise`: ``` $ npm install eslint-plugin-promise --save-dev ``` **Note:** If you installed ESLint globally (using the `-g` flag) then you must also install `eslint-plugin-promise` globally. ## Usage Add `promise` to the plugins section of your `.eslintrc.json` configuration file. You can omit the `eslint-plugin-` prefix: ```json { "plugins": ["promise"] } ``` Then configure the rules you want to use under the rules section. ```json { "rules": { "promise/always-return": "error", "promise/no-return-wrap": "error", "promise/param-names": "error", "promise/catch-or-return": "error", "promise/no-native": "off", "promise/no-nesting": "warn", "promise/no-promise-in-callback": "warn", "promise/no-callback-in-promise": "warn", "promise/avoid-new": "warn", "promise/no-new-statics": "error", "promise/no-return-in-finally": "warn", "promise/valid-params": "warn" } } ``` or start with the recommended rule set: ```json { "extends": ["plugin:promise/recommended"] } ``` ## Rules | rule | description | recommended | fixable | | -------------------------------------------------------- | -------------------------------------------------------------------------------- | ----------- | -------- | | [`catch-or-return`][catch-or-return] | Enforces the use of `catch()` on un-returned promises. | :bangbang: | | | [`no-return-wrap`][no-return-wrap] | Avoid wrapping values in `Promise.resolve` or `Promise.reject` when not needed. | :bangbang: | | | [`param-names`][param-names] | Enforce consistent param names and ordering when creating new promises. | :bangbang: | | | [`always-return`][always-return] | Return inside each `then()` to create readable and reusable Promise chains. | :bangbang: | | | [`no-native`][no-native] | In an ES5 environment, make sure to create a `Promise` constructor before using. | | | | [`no-nesting`][no-nesting] | Avoid nested `then()` or `catch()` statements | :warning: | | | [`no-promise-in-callback`][no-promise-in-callback] | Avoid using promises inside of callbacks | :warning: | | | [`no-callback-in-promise`][no-callback-in-promise] | Avoid calling `cb()` inside of a `then()` (use [nodeify][] instead) | :warning: | | | [`avoid-new`][avoid-new] | Avoid creating `new` promises outside of utility libs (use [pify][] instead) | | | | [`no-new-statics`][no-new-statics] | Avoid calling `new` on a Promise static method | :bangbang: | :wrench: | | [`no-return-in-finally`][no-return-in-finally] | Disallow return statements in `finally()` | :warning: | | | [`valid-params`][valid-params] | Ensures the proper number of arguments are passed to Promise functions | :warning: | | | [`prefer-await-to-then`][prefer-await-to-then] | Prefer `await` to `then()`/`catch()`/`finally()` for reading Promise values | :seven: | | | [`prefer-await-to-callbacks`][prefer-await-to-callbacks] | Prefer async/await to the callback pattern | :seven: | | **Key** | icon | description | | ---------- | ----------------------------------------------- | | :bangbang: | Reports as error in recommended configuration | | :warning: | Reports as warning in recommended configuration | | :seven: | ES2017 Async Await rules | | :wrench: | Rule is fixable with `eslint --fix` | ## Maintainers - Jamund Ferguson - [@xjamundx][] - Macklin Underdown - [@macklinu][] ## License - (c) MMXV jden <mailto:jason@denizac.org> - ISC license. - (c) 2016 Jamund Ferguson <mailto:jamund@gmail.com> - ISC license. [catch-or-return]: docs/rules/catch-or-return.md [no-return-wrap]: docs/rules/no-return-wrap.md [param-names]: docs/rules/param-names.md [always-return]: docs/rules/always-return.md [no-native]: docs/rules/no-native.md [no-nesting]: docs/rules/no-nesting.md [no-promise-in-callback]: docs/rules/no-promise-in-callback.md [no-callback-in-promise]: docs/rules/no-callback-in-promise.md [avoid-new]: docs/rules/avoid-new.md [no-new-statics]: docs/rules/no-new-statics.md [no-return-in-finally]: docs/rules/no-return-in-finally.md [valid-params]: docs/rules/valid-params.md [prefer-await-to-then]: docs/rules/prefer-await-to-then.md [prefer-await-to-callbacks]: docs/rules/prefer-await-to-callbacks.md [nodeify]: https://www.npmjs.com/package/nodeify [pify]: https://www.npmjs.com/package/pify [@macklinu]: https://github.com/macklinu [@xjamundx]: https://github.com/xjamundx