PromisedArray

PromisedArray combines the interface of Promise and Array.

• It is a native Promise. You can use it in a promise chain and with the await operator.
• It includes all members of Array.prototype. They will apply to the array, which the promise resolves to and they return a promise to the result of the original method.
• Methods of Array.prototype, which expect callbacks, accept also asynchronous callbacks. They will wait, until the callback's promise resolves and continue with the result.
• No need to mark the callback by the async keyword, if they don't use teh await keyword and just return a promise.
• Callback execution possible either sequentially or concurrently.
• No dependencies on other modules.

Warnig: still in the development.

Table of Contents

• Synopsis
• Description

Synopsis

// Print an array of names of items with the specified keys.
new PromisedArray([1, 2, 3])
  .map(key => fetch('https://server.com/items/' + key))
  .map(response => response.json().name)
  .then(names => console.log(names))
  .catch(error => console.error(error))

Description

PromisedArray is a function object with the prototype combined from Promise and Array. Instances can be constructed either from an array or from a promise resolving to an array.

// Print names of all items.
const promise = fetch('https://server.com/items')
  .then(response => response.json())
PromisedArray
  .fromPromise(promise)
  .forEach({ name } => console.log(name))
  .catch(console.error)

Methods of the PromisedArray prototype, which share their names with their corresponding methods of the original Array prototype, have the same semantics and guarantees the same order of processing array items. They return the same result, only wrapped in a PromisedArray instance, if it is an array, or in a stqndqrd promise in other cases. Methods, which accept callbacks as parameters, check, if the result of the callback is a promise or not. If it is, they wait for its resolution and continue with the result. If the promise gets rejected, the whole result promise will be rejected and the loop over array items aborted.

Methods which end with Concurrently execute callbacks for every array item concurrently and wait for resulution of all promises for callback call results, before they process the results. The order callback execution may differ from the original method from the Array prototype. If the method returns an array, order of results in that array is guaranteed to be the same as the original method from the Array prototype would return.

License

Copyright (c) 2019 Ferdinand Prantl

Licensed under the MIT license.