eslint-plugin-promise

What is eslint-plugin-promise?

The eslint-plugin-promise package is an ESLint plugin that enforces best practices and common idioms for dealing with promises in JavaScript. It provides a set of rules that catch common mistakes and enforce conventions when working with promises.

What are eslint-plugin-promise's main functionalities?

Avoiding creation of new promises outside of utility libraries

This rule ensures that the executor function of a new Promise has the parameters named 'resolve' and 'reject'.

/* eslint promise/param-names: 'error' */
new Promise((resolve, reject) => { /* executor function */ });

Ensuring that each time a then() is applied to a promise, a catch() is applied as well

This rule enforces the use of catch() on unhandled promises.

/* eslint promise/catch-or-return: 'error' */
promise.then(function(data) {
  // handle data
}).catch(function(error) {
  // handle error
});

Enforcing the return of a promise in certain contexts

This rule ensures that promise chains always return a value, preventing silent failures and unhandled rejections.

/* eslint promise/always-return: 'error' */
function foo() {
  return doSomething().then(function() {
    // do something else
    return 'result';
  });
}

Other packages similar to eslint-plugin-promise

eslint-plugin-async-await

This plugin provides ESLint rules for async/await syntax, which is related to promises. It helps to enforce best practices and catch common mistakes when using async/await, but it does not focus on promises directly.

eslint-plugin-standard

Part of the 'eslint-plugin-standard' plugin includes rules that are applicable to promises, as it adheres to the JavaScript Standard Style. However, it covers a broader range of JavaScript features and is not solely focused on promises.

README

eslint-plugin-promise

Enforce best practices for JavaScript promises.

• Installation
• Usage
• Rules
• Maintainers
• License

Installation

You'll first need to install ESLint:

$ 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 configuration file. You can omit the eslint-plugin- prefix:

{
  "plugins": ["promise"]
}

Then configure the rules you want to use under the rules section.

{
  "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

{
  "extends": ["plugin:promise/recommended"]
}

Rules

rule	description	recommended	fixable
catch-or-return	Enforces the use of catch() on un-returned promises.	:bangbang:
no-return-wrap	Avoid wrapping values in Promise.resolve or Promise.reject when not needed.	:bangbang:
param-names	Enforce consistent param names when creating new promises.	:bangbang:	:wrench:
always-return	Return inside each then() to create readable and reusable Promise chains.	:bangbang:
no-native	In an ES5 environment, make sure to create a Promise constructor before using.
no-nesting	Avoid nested then() or catch() statements	:warning:
no-promise-in-callback	Avoid using promises inside of callbacks	:warning:
no-callback-in-promise	Avoid calling cb() inside of a then() (use nodeify instead)	:warning:
avoid-new	Avoid creating new promises outside of utility libs (use pify instead)
no-new-statics	Avoid calling new on a Promise static method	:bangbang:
no-return-in-finally	Disallow return statements in finally()	:warning:
valid-params	Ensures the proper number of arguments are passed to Promise functions	:warning:
prefer-await-to-then	Prefer await to then() for reading Promise values	:seven:
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:[e-mail] - ISC license.
• (c) 2016 Jamund Ferguson mailto:[e-mail] - ISC license.