https://github.com/psaia/fast-observer

A blazingly fast asynchronous O(1)-capable event dispatcher.
https://github.com/psaia/fast-observer

event-dispatcher observer pubsub typescript

Last synced: about 1 month ago
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A blazingly fast asynchronous O(1)-capable event dispatcher.

• Host: GitHub
• URL: https://github.com/psaia/fast-observer
• Owner: psaia
• License: apache-2.0
• Created: 2019-10-14T02:31:42.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2022-12-30T18:51:23.000Z (almost 2 years ago)
• Last Synced: 2024-08-02T05:23:37.109Z (4 months ago)
• Topics: event-dispatcher, observer, pubsub, typescript
• Language: TypeScript
• Homepage: https://www.npmjs.com/package/fast-observer
• Size: 37.1 KB
• Stars: 1
• Watchers: 2
• Forks: 1
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-blazingly-fast - fast-observer - A blazingly fast asynchronous O(1)-capable event dispatcher. (TypeScript)

README

        
# Fast Observer [![Build Status](https://travis-ci.org/psaia/fast-observer.svg?branch=master)](https://travis-ci.org/psaia/fast-observer)

**Does the world need another event dispatcher library?**

Most event dispatchers are O(N). Fast Observer is a lightweight O(1) and

asynchronous library. This is useful when:

* Performance matters (think mouse events or `requestAnimationFrame()`)

* You want to work with async/await on publishing

* You care about file size

* Convenience features such as namespaces aren't necessary

* Works in the browser, on the server, and when doing SSR

Some extra tidbits:

* There are zero-dependencies

* It's well tested with benchmarks @see [Performance](#performance)

### Installation

```

npm i --save fast-observer

```

### Performance

It's unnecessary to profile the `publishFast` method. It's going to be as fast

as calling a function directly.

However, the O(N) `publish()` method is 14.5 times faster the most popular

event dispatcher library called [PubSub-js](https://github.com/mroderick/PubSubJS).

* fast-observer: `Executed 10000000 times in 436 ms`

* PubSub-js: `Executed 10000000 times in 6341 ms`

See benchmarks [here](benchmark/). I'd be happy to adjust or add more

benchmarks if requested.

### Usage

```typescript

import Observer from "fast-observer";

const o = new Observer();

// Define some O(N) subscriptions (nothing new here).

o.subscribe("launch ship", launchTheShip);

o.subscribe("launch ship", launchTheOtherShip);

o.subscribe("launch ship", launchTheOtherShip);

await o.publish("launch ship"); // Wait for all the ships to launch.

// Define O(1) subscription.

o.subscribeFast("engine propulsion", handlePropulsion);

await o.publishFast("engine propulsion"); // Similar to publish, is a promise.

```

The major caveat of `subscribeFast` is that there can only be one. If there are

multiple, they will override each other. There's no magic here -

`subscribeFast` and `publishFast` is just more of structured way to call a

function.

### API

* `subscribe(eventName: string, (payload?: any) => void | Promise): void`

* `unsubscribe(eventName: string, fn): void`

* `subscribeFast(eventName: string, (payload?: any) => void | Promise): void`

* `unsubscribeFast(eventName: string): void`

* `publish(eventName: string): Promise`

* `publishFast(eventName: string): Promise`

### Development

1. `npm i && tsc -w` to install dev-deps & watch

2. `npm test` to run tests

## License

Apache Version 2.0

See [LICENSE](https://github.com/psaia/fast-observer/blob/master/LICENSE)