@omts/deferred ⏳

A simple and flexible implementation of the deferred pattern in TypeScript. This package allows you to create a Promise and control its resolution and rejection externally, making it ideal for managing complex asynchronous workflows.

Installation 📦

You can install the package via npm or pnpm:

npm install @omts/deferred

or

pnpm add @omts/deferred

Usage ✨

This package exports a Deferred class, which provides a promise object, along with resolve and reject methods to manually handle promise state. Below is an example of how to use it:

import { Deferred } from '@omts/deferred';

// Create a new Deferred instance
const deferred = new Deferred<string>();

// Example usage: Resolve the promise after a delay
setTimeout(() => {
  deferred.resolve("Success!");
}, 1000);

// Consume the promise
deferred.promise.then(result => {
  console.log(result); // Output: "Success!"
}).catch(err => {
  console.error(err);
});

Methods:

• resolve(value: T): Resolves the promise with the given value.
• reject(reason?: any): Rejects the promise with the specified reason.
• promise: The Promise instance which can be awaited or handled with .then().

Parameters:

• T: The type of value that will be resolved by the promise.

Complexity 📊

• Time Complexity: O(1) for resolving or rejecting the promise.
• Space Complexity: O(1) as only a few references (the promise, resolve, and reject functions) are maintained.

Example: Handling Asynchronous Events 💡

You can use Deferred to manage asynchronous events, making it easier to handle event-based or callback-driven code:

import { Deferred } from '@omts/deferred';

const deferred = new Deferred<string>();

// Simulate an API call or asynchronous operation
setTimeout(() => {
  deferred.resolve("Data received!");
}, 2000);

deferred.promise.then((result) => {
  console.log(result); // Output: "Data received!"
});

Development 🛠️

Bun and Development Setup

We recommend using Bun as the development tool. Follow the steps below for development and testing:

1. Clean: Remove the dist directory.

   pnpm run clean

2. Build: Generate ES and CommonJS formats.

   pnpm run build

3. Test: Run the tests using the Bun test runner.

   pnpm run test

Scripts

• clean: Remove the dist directory.
  pnpm run clean

• build: Run a clean build and generate outputs in ES and CommonJS formats.
  pnpm run build

• test: Run all tests using Bun.
  pnpm run test

• tdd: Run tests in watch mode.
  pnpm run tdd

Contributing 🤝

Contributions are welcome! If you have any improvements, bug fixes, or new ideas, feel free to open an issue or submit a pull request (PR).

License ⚖️

This project is licensed under the MIT License - see the LICENSE file for details.

Happy async coding! 🎉