@bitty/deferred

It provides a function to create Deferred objects. They contain a Promise and methods to imperatively resolve or reject it.

• 📦 Distributions in ESM, CommonJS, UMD and UMD minified formats.

• ⚡ Lightweight:

  • Weighs less than 1KB (min + gzip).
  • Tree-shakeable.
  • Side-effects free.

• 🔋 Bateries included:

  • No dependencies.
  • Only requires Promise, but you can use a polyfill in unsupported environments.
  • Isn't based in other es2015+ features or APIs.

• 🏷 Safe:

  • JSDocs and type declarations for IDEs and editor's autocomplete/intellisense.
  • Made with TypeScript as strict as possible.
  • Unit tests with AVA.

Installation

This library is published in the NPM registry and can be installed using any compatible package manager.

npm install @bitty/deferred --save

# For Yarn, use the command below.
yarn add @bitty/deferred

Installation from CDN

This module has a UMD bundle available through JSDelivr and Unpkg CDNs.

<!-- For UNPKG use the code below. -->
<script src="https://unpkg.com/@bitty/deferred"></script>

<!-- For JSDelivr use the code below. -->
<script src="https://cdn.jsdelivr.net/npm/@bitty/deferred"></script>

<script>
  // UMD module defines "createDeferred" in global/window scope.
  console.log(createDeferred);
  //=> "[Function: createDeferred]"

  let deferred = createDeferred();

  deferred.promise.then(() => {
    console.log('It was okay.');
  });

  deferred.resolve();
</script>

Getting Stated

This module default exports createDeferred, which is a factory function that creates Deferred objects.

import createDeferred from '@bitty/deferred';

const deferred = createDeferred<boolean>();

Deferred objects exposes a Promise and methods to reject or resolve it.

import createDeferred, { Deferred } from '@bitty/deferred';

let deferred: Deferred<number>;

// ...

deferred.promise
  .then(value => console.log(`You received $ ${value.toFixed(2)}!`))
  .catch(reason => console.error(`Couldn't receive because of `, reason));

deferred.resolve(10);
//=> It logs "You received $ 50.00!" in the console.

deferred.reject(new Error('The account number is invalid.'));
//=> Won't log anything because promise is already resolved.

We also export the Deferred interface. Which simply defines the promise property (an instance of Promise) and the methods that change it.

interface Deferred<T> {
  readonly promise: Promise<T>;
  reject(reason: unknown): void;
  resolve(value: T | PromiseLike<T>): void;
}

License

Released under MIT License.