Async/await utility functions

This library provides control flow utility functions for async/await. Since async/await returns promises, you can also use it with plain .then and .catch. Includes the following:

• paralell - Run any number of tasks in parallel
• parallelLimit Runs maximum of {limit} number of tasks in parallel
• waterfall - Run tasks one by one, passing down the result of previous task
• series - Runs tasks in a series

Instalation

npm install async-await-control

or if you use yarn

yarn add async-await-control

Usage

Parallel / Parallel limit

Run any number of tasks in parallel

Parameters

| Name | Type | Description | | ----- | :--------------: | :-------------------------------------------------------------------------------------------- | | tasks | Iterable|Object | A collection of async functions to run. Each async function must return a Promise or a value. | | limit | Number | (Optional) Limit the number of parallel tasks |

// tasks can be Array/Iterable/Object
const tasks = {
  first: () => Promise.resolve(1),
  second: () => Promise.resolve(2),
  third: () => Promise.resolve(3)
};

const res = await parallel(tasks, 2);
// { first: 1, second: 2, third: 3 }

Waterfall

Run tasks one by one, passing down the result of previous task

Waterfall

| Name | Type | Description | | ----- | :------: | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | tasks | Iterable | An array of async functions to run. Each function should complete with any number of result values. The result values will be passed as arguments, in order, to the next task. |

Returns array of results or a single value if only single value is passed in the last iteratee.

const tasks = [
  () => Promise.resolve(1),
  (a) => Promise.resolve([1, 2]), // a = 1
  (a, b) => Promise.resolve([3, 4]), // a = 1, b = 2
];

const res = await waterfall(tasks);
// [4, 5]


const tasks = [
  () => Promise.resolve(1),
  (a) => Promise.resolve([1, 2]), // a = 1
  (a, b) => Promise.resolve(3), // a = 1, b = 2
];

const res = await waterfall(tasks);
// 3

Series

Runs tasks in a series

Series

| Name | Type | Description | | ----- | :------: | :------------------------------------------------------------------------------------ | | tasks | Iterable | An array of async functions to run. Each function should return a Promise or a value. |

const tasks = [
  () => Promise.resolve(1),
  () => Promise.resolve([1, 2]),
  () => Promise.resolve([3, 4]),
];

const res = await waterfall(tasks);
// [1, [1, 2], [3, 4]]