Table of Contents
- Resources, Blogs, and Books
- Promises/A+ Implementations (ES6/ES2015 compatible)
- Convenience Utilities
Resources, Blogs, and Books
- Promise Cookbook – The why, what, and how. “A brief introduction […] primarily aimed at frontend developers”.
- Promises for Asynchronous Programming – Chapter from Exploring ES6
- You Don’t Know JS: Promises – Chapter from You Don’t Know JS: Async & Performance
- Promise it won’t hurt – An interactive nodeschool workshop
- ES6 Kata Promises – Promises Katas : Basics
- ES6 Promises in Depth
- An Incremental Tutorial on Promises – An FAQ styled tutorial for beginners.
- Promise Fun – @sindresorhus’s notes, patterns, and solutions to common Promise problems
- You’re Missing the Point of Promises – Promises are much more than callback aggregation, and that jQuery’s implementation (prior to 3.0) isn’t enough.
- We have a problem with promises – “Many of us are using promises without really understanding them.”
- Promise anti-patterns – Common misuses and how to avoid them.
- Promise anti-patterns (2) – Another set of promises anti-patterns
- Promise Ponderings, (Anti-)Patterns, and Apologies – Promise behaviour demonstrated and explained by common questions and their answers.
- Writing Promise-Using Specifications – “This document gives guidance on how to write specifications that create, accept, or manipulate promises”
- Async functions – making promises friendly
- Promises/A+ specification
- caniuse promises
- Fates and States – Quick definitions of possible states.
- Promisees – Promise visualization playground for the adventurous.
Promises/A+ Implementations (ES6/ES2015 compatible)
These implement no more or less than the es6 spec. They make great polyfills and are exceptionally compatible with native promises.
- pinkie – Ponyfill. Node-oriented, but browserifyable. Extremely small implementation.
- native-promise-only – Polyfill. Browser and node-compatible.
- es6-promise – Opt-in polyfill. A strict-spec subset of rsvp.js.
- lie – Small, browserifyable with an opt-in polyfill.
Implementations with extras
All of these provide more features than the language yet remain compatible. Node + Browsers for all.
- bluebird – Fully featured, extremely performant. Long stack traces & generator/coroutine support.
- creed – Hyper performant & full featured like Bluebird, but FP-oriented. Coroutines, generators, promises, ES2015 iterables, & fantasy-land spec.
- rsvp.js – Lightweight with a few extras. Compatible down to IE6!
- Q – One of the original implementations. Long stack traces and other goodies.
- then/promise – Small with
- when.js – Packed with control flow, functional, and utility methods.
- native-or-bluebird – Helps transition to completely native.
- pinkie-promise – Use native, or fall back to
pinkie. Great for node library authors.
- any-promise – Loads the first available implementation. Safe for browserify.
Native and strictly spec-compliant promises are awesome for compatibility, future-proofness, library authors, and browsers. However, libraries like bluebird patch goodies onto the
Promise constructor and prototype. Solution? tiny modules of course!
- delay – Delay a promise a specified amount of time.
- pify – Promisify (“denodify”) a callback-style function.
- loud-rejection – Make unhandled promise rejections fail loudly instead of the default silent fail.
- hard-rejection – Make unhandled promise rejections fail hard right away instead of the default silent fail
- p-queue – Promise queue with concurrency control
- p-break – Break out of a promise chain
- p-lazy – Create a lazy promise that defers execution until
- p-defer – Create a deferred promise
- p-if – Conditional promise chains
- p-tap – Tap into a promise chain without affecting its value or state
- p-map – Map over promises concurrently
- p-all – Run promise-returning & async functions concurrently with optional limited concurrency
- p-limit – Run multiple promise-returning & async functions with limited concurrency
- p-times – Run promise-returning & async functions a specific number of times concurrently
- p-catch-if – Conditional promise catch handler
- p-time – Measure the time a promise takes to resolve
- p-log – Log the value/error of a promise
- p-filter – Filter promises concurrently
- p-settle – Settle promises concurrently and get their fulfillment value or rejection reason
- p-memoize – Memoize promise-returning & async functions
- p-whilst – Calls a function repeatedly while a condition returns true and then resolves the promise
- p-throttle – Throttle promise-returning & async functions
- p-debounce – Debounce promise-returning & async functions
- p-retry – Retry a promise-returning or async function
- p-wait-for – Wait for a condition to be true
- p-timeout – Timeout a promise after a specified amount of time
- p-race – A better
- p-try –
Promise#try()ponyfill – Starts a promise chain
- p-finally –
Promise#finally()ponyfill – Invoked when the promise is settled regardless of outcome
- p-any – Wait for any promise to be fulfilled
- p-some – Wait for a specified number of promises to be fulfilled
- p-pipe – Compose promise-returning & async functions into a reusable pipeline
- p-each-series – Iterate over promises serially
- p-map-series – Map over promises serially
- p-reduce – Reduce a list of values using promises into a promise for a value
- p-props – Like
- promise-method – Standalone
bluebird.method. Turn a synchronously-returning method into a promise-returning one.
- is-promise – Determine if something looks like a Promise.
- sprom – Resolve when a stream ends. Optional buffering (be careful with this!)
- task.js – Write async functions in a blocking style using promises and generators. Like
- co – Like
bluebird.coroutine, but supports thunks too.
- lie-fs – Promise wrappers for Node’s FS API.
- promise-do-until – Calls a function repeatedly until a condition returns true and then resolves the promise.
- promise-do-whilst – Calls a function repeatedly while a condition returns true and then resolves the promise.
- promise-semaphore – Push a set of work to be done in a configurable serial fashion
- promise-nodeify – Standalone
nodeifymethod which calls a Node-style callback on resolution or rejection.