> For the complete documentation index, see [llms.txt](https://strctr.gitbook.io/programming/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://strctr.gitbook.io/programming/01-languages/javascript/01-language/e-controls/e4-promises/09-promises-patterns.md).

# 09. Promise Patterns

* [x] [`promise-fun` by sindresorhus](https://github.com/sindresorhus/promise-fun)
* [x] [Decorating Async Javascript Functions](http://innolitics.com/10x/javascript-decorators-for-promise-returning-functions/)
* [x] [`bluebird` API reference](http://bluebirdjs.com/docs/api-reference.html)

## Control abstractions:

* [`p-if`](https://github.com/sindresorhus/p-if) - execute `then` handler if match some predicate.
* [`p-catch-if`](https://github.com/sindresorhus/p-catch-if) - evaluate predicate on error type at `catch` block.
* [`p-whilst`](https://github.com/sindresorhus/p-whilst) - async version of the `while` statement.
* [`p-do-whilst`](https://github.com/sindresorhus/p-do-whilst) - async version of the `do…while` statement.
* [`p-forever`](https://github.com/sindresorhus/p-forever) - async version of `while (true) {}`.
* [`p-wait-for`](https://github.com/sindresorhus/p-wait-for) - wait for a condition to be `true`.
* [`p-finally`](https://github.com/sindresorhus/p-finally) - `Promise.finally()`.
* [`p-try`](https://github.com/sindresorhus/p-try) - `Promise.try()`.

## Execution strategies:

* [`p-retry`](https://github.com/sindresorhus/p-retry) - retry async function.
* [`p-cancellable`](https://github.com/sindresorhus/p-cancelable) - create a promise that can be canceled.
* [`p-progress`](https://github.com/sindresorhus/p-progress) - create a promise that reports progress.
* [`p-reflect`](https://github.com/sindresorhus/p-reflect) - promise always fulfill with its actual fulfillment value or rejection reason.
  * [`p-settle`](https://github.com/sindresorhus/p-settle) - same as `p-reflect` but for array of promises.
* [`p-times`](https://github.com/sindresorhus/p-times) - run async function a specific number of times concurrently.

## Timings:

* [`delay`](https://github.com/sindresorhus/delay) - resolve promise with delay.
* [`nanodelay`](https://github.com/ai/nanodelay) - A tiny (28 bytes) Promise wrapper around `setTimeout`.
* [`p-min-delay`](https://github.com/sindresorhus/p-min-delay) - delay a promise a minimum amount of time.
* [`p-timeout`](https://github.com/sindresorhus/p-timeout) - reject promise after a specified amount of time.
* [`p-immediate`](https://github.com/sindresorhus/p-immediate) - returns a promise resolved in the next event loop - think `setImmediate()`.

## Executors:

* [`p-map`](https://github.com/sindresorhus/p-map) - run async functions multiple times with different inputs concurrently.
* [`p-filter`](https://github.com/sindresorhus/p-filter) - run async functions multiple times with different inputs concurrently and get a filtered down result.
* [`p-reduce`](https://github.com/sindresorhus/p-reduce) - reduce a list of values using promises into a promise for a value.
* [`p-all`](https://github.com/sindresorhus/p-all) - same as `Promise.all()`, but accepts functions instead of promises directly so you can limit the concurrency.
* [`p-race`](https://github.com/sindresorhus/p-race) - fixes the silly behavior of `Promise.race()` returning a forever pending promise. when supplied an empty iterable, which could create some really hard to debug problems.
* [`p-any`](https://github.com/sindresorhus/p-any) - return the fastest promise. Use this instead of `Promise.race()`.
* [`p-some`](https://github.com/sindresorhus/p-some) - use when you need the fastest of multiple promises.
* [`p-every`](https://github.com/kevva/p-every) - like `Array.every` for promises.
* [`p-one`](https://github.com/kevva/p-one) - like `Array.some` for promises.
* [`p-locate`](https://github.com/sindresorhus/p-locate) - get the first fulfilled promise that satisfies the provided testing function.
* [`p-limit`](https://github.com/sindresorhus/p-limit) - run multiple async functions with limited concurrency.
* [Bluebird: `Promise.join`](http://bluebirdjs.com/docs/api/promise.join.html#promise.join) - same as `Promise.all()`, but for fixed amount of discrete promises that you want to coordinate concurrently (more performant).

## Promise data/execution structures:

* [`p-queue`](https://github.com/sindresorhus/p-queue) - promise queue with concurrency control.
* [`p-series`](https://github.com/sindresorhus/p-series) - run async functions in series.
  * [`p-map-series`](https://github.com/sindresorhus/p-map-series) - serial `Promise.all` with mapper function.
  * [`p-each-series`](https://github.com/sindresorhus/p-each-series) - iterate over promises serially.
* [`p-pipe`](https://github.com/sindresorhus/p-pipe) - compose async functions into a reusable pipeline.
* [`p-waterfall`](https://github.com/sindresorhus/p-waterfall) - run async functions in series, each passing its result to the next.
* [`p-props`](https://github.com/sindresorhus/p-props) - like `Promise.all()` but for `Map` and `Object`.
* [`mux`](https://github.com/ide/mux) - creates a promise that waits for the promises in nested data structures and resolves to data structures of the same form. It recursively traverses the input data structure and multiplexes its promises.

## Functional Programming

* [`p-debounce`](https://github.com/sindresorhus/p-debounce) - debounce async functions.
* [`p-throttle`](https://github.com/sindresorhus/p-throttle) - throttle async functions.
* [`p-memoize`](https://github.com/sindresorhus/p-memoize) - memoize promises caching the result of calls with identical input.
* [`reuse-promise`](https://github.com/elado/reuse-promise) - reuse the same promise that's returned from a function until it's resolved.
* [`p-lazy`](https://github.com/sindresorhus/p-lazy) - create a lazy promise that defers execution until `.then()` or `.catch()` is called.

## Utils:

* [`pify`](https://github.com/sindresorhus/pify) - promisify callback or CPS style functions.
* [`p-event`](https://github.com/sindresorhus/p-event) - promisify event (once).
* [`p-tap`](https://github.com/sindresorhus/p-tap) - access to promise value without chaining promise.
* [`p-log`](https://github.com/sindresorhus/p-log) - log the value/error of a promise.
* [`p-time`](https://github.com/sindresorhus/p-time) - measure the time a promise takes to resolve.
* [Bluebird: `Promise.method`](http://bluebirdjs.com/docs/api/promise.method.html#promise.method) - wraps the given function into new function. The new function will always return a promise that is fulfilled with the original functions return values or rejected with thrown exceptions from the original function.

## Error Handling

* [`await-to-js`](https://github.com/scopsy/await-to-js) - convert Promise to `[err, data]` outcome.
* [`catchify`](https://github.com/majgis/catchify) - various error handling strategies for Promise.
* [Bluebird: filtered `catch`](http://bluebirdjs.com/docs/api/catch.html#filtered-catch)
* [Bluebird: `.error`](http://bluebirdjs.com/docs/api/catch.html#filtered-catch)
* [Bluebird:  Resource management](http://bluebirdjs.com/docs/api/resource-management.html#resource-management)
  * [`.disposer`](http://bluebirdjs.com/docs/api/disposer.html), objects that wrap a resource and a method to release that resource, together with.
  * [`Promise.using`](http://bluebirdjs.com/docs/api/promise.using.html#promise.using), a function to safely use disposers in a way that automatically calls their release method.

## Rejections

* [`loud-rejection`](https://github.com/sindresorhus/loud-rejection)
* [`hard-rejection`](https://github.com/sindresorhus/hard-rejection)


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