https://github.com/susisu/tyde

Typed event emitter
https://github.com/susisu/tyde

Last synced: 28 days ago
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Typed event emitter

• Host: GitHub
• URL: https://github.com/susisu/tyde
• Owner: susisu
• License: mit
• Created: 2019-10-28T04:25:48.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2024-04-03T17:09:44.000Z (7 months ago)
• Last Synced: 2024-10-01T07:02:51.155Z (about 1 month ago)
• Language: TypeScript
• Homepage:
• Size: 450 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# @susisu/tyde

[![CI](https://github.com/susisu/tyde/workflows/CI/badge.svg)](https://github.com/susisu/tyde/actions?query=workflow%3ACI)

Typed event emitter

## Installation

``` shell

# npm

npm i @susisu/tyde

# yarn

yarn add @susisu/tyde

# pnpm

pnpm add @susisu/tyde

```

## Usage

tyde provides API that is similar to [EventEmitter](https://nodejs.org/api/events.html) and [event-kit](https://github.com/atom/event-kit).

The simplest usage is subscribing events with `.on()` and emitting events with `.emit()`.

``` typescript

import { Emitter } from "@susisu/tyde";

const emitter = new Emitter();

const subscription = emitter.on("change", value => {

  console.log(value);

});

emitter.emit("change", 42); // -> 42

```

Subscriptions can be unsubscribed by calling `.unsubscribe()`.

``` typescript

subscription.unsubscribe();

emitter.emit("change", 0); // no output

```

The curried version of `.on()` is also available.

``` typescript

const onChange = emitter.on("change");

const subscription = onChange(value => { /* ... */ });

```

You can optionally restrict types of emitted values by giving a dictionary to `Emitter`'s type parameter.

``` typescript

const emitter = new Emitter<{

  "change": number,

  "destroy": void,

}>();

emitter.emit("change", 42);     // ok

emitter.emit("destroy");        // ok

emitter.emit("foo", 42);        // type error: unknown event

emitter.emit("change", "test"); // type error: mismatched type

```

## Difference from other event emitters

By design, tyde has some difference from other event emitter libraries:

- No wildcards, because of the strongly typed interface.

- Events are emitted asynchronously by default.

  - Usually event handlers should not care whether it is called synchronously or asynchronously.

  - There is also a synchronous version `.emitSync()`, but it is not generally recommended.

- Invocation order of event handlers is not guaranteed in any way.

  - Specifying execution order in a less explicit way will lower the readability of code.

  - If you still want one, invoke functions sequentially in one event handler, or separate the event into multiple stages.

## License

[MIT License](http://opensource.org/licenses/mit-license.php)

## Author

Susisu ([GitHub](https://github.com/susisu), [Twitter](https://twitter.com/susisu2413))