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https://github.com/slorber/micro-typed-events
The smallest, most convenient typesafe TS event emitter you'll ever need
https://github.com/slorber/micro-typed-events
event-emitter event-listener events javascript listener pubsub stream typescript
Last synced: about 2 months ago
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The smallest, most convenient typesafe TS event emitter you'll ever need
- Host: GitHub
- URL: https://github.com/slorber/micro-typed-events
- Owner: slorber
- License: mit
- Created: 2019-03-08T08:36:57.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2022-12-09T15:05:36.000Z (about 2 years ago)
- Last Synced: 2024-10-03T12:24:26.768Z (3 months ago)
- Topics: event-emitter, event-listener, events, javascript, listener, pubsub, stream, typescript
- Language: TypeScript
- Homepage: https://sebastienlorber.com
- Size: 966 KB
- Stars: 42
- Watchers: 4
- Forks: 1
- Open Issues: 16
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# micro-typed-events
[](https://www.npmjs.com/package/micro-typed-events)
[](https://travis-ci.com/slorber/micro-typed-events)
```ts
const events = createEvents();
const unsubscribe = events.subscribe(num => console.log(num));
events.emit(42);
events.emit(57);
unsubscribe();
events.emit(99); // not logged
events.emit('hey'); // not compiling
```
The smallest, most convenient, typesafe (with TS, but also works with normal JS), event emitter / pubsub system you'll ever need.
Unlike other event emitters, it does not use `on/off/once` methods but only a single subscribe method and returns an unsubscribe handle, which makes it more tiny, easier to type, more convenient to use with arrow functions.
The most minimal code you need for a typesafe pub/sub system, and **feature complete**, making suitable to include as a dependency on other libraries.
## Install
```bash
npm install --save micro-typed-events
// or
yarn add micro-typed-events
```
## Usage
**Simple typed events**
```ts
import { createEvents } from 'micro-typed-events';
const events = createEvents();
const unsubscribe = events.subscribe(num => console.log(num));
events.emit(42);
events.emit('hey'); // Does not compile
unsubscribe();
```
---
**Object typed events**
```ts
import { createEvents } from 'micro-typed-events';
type EventType = { num: number; str: string };
const events = createEvents();
const unsubscribe = events.subscribe(obj => console.log(obj));
events.emit({ num: 42, str: 'hello' });
events.emit({ num: 42, str: null }); // Does not compile
unsubscribe();
```
---
**Multiple-args typed events**
```ts
import { createEvents } from 'micro-typed-events';
const events = createEvents();
const unsubscribe = events.subscribe((num, str) => console.log(num, str));
events.emit(42, 'hello');
events.emit('hello', 42); // Does not compile
unsubscribe();
```
---
**Advanced typing, dynamic args...**
```ts
import { createEvents } from 'micro-typed-events';
// Listener type is any void function
type ListenerType = (str: string, num: number, ...args: any[]) => void;
const events = createEvents();
const unsubscribe = events.subscribe((str, num, ...args) =>
console.log(str, num, ...args),
);
events.emit('hey', 1, 'blaa', 'whatever', 'you', 'want', 1, 2, 3);
events.emit(1, 'hey', 'blaa', 'whatever', 'you', 'want', 1, 2, 3); // Does not compile
unsubscribe();
```
---
**Vanilla JS**
```js
import { createEvents } from 'micro-typed-events';
const events = createEvents();
const unsubscribe = events.subscribe(num => console.log(num));
events.emit(42);
events.emit('hey'); // Does not fail, you should use typescript
unsubscribe();
```
## FAQ
**Should I create a single events object for all my events?**
No, you should rather create one per event-type. You could expose all your events as an object, like this:
```ts
export const ApiEvents = {
requests: createEvents(),
responses: createEvents(),
errors: createEvents(),
};
```
**Can I unsubscribe directly inside a listener**
Yes, listeners are able to unsubscribe themselves (or other listeners) without messing things up.
**Can I subscribe directly inside a listener**
Yes, but that listener will only be called on next emitted event.
**Can I embed this library in my library?**
Yes, this lib is very tiny. It exports ES and CJS modules. Here's the CJS output, I'll let you judge yourself if you can write something shorter:
```js
'use strict';
Object.defineProperty(exports, '__esModule', { value: true });
function createEvents() {
var listeners = [];
return {
subscribe: function (listener) {
listeners.push(listener);
return function () {
var index = listeners.indexOf(listener);
if (index > -1) {
listeners.splice(index, 1);
}
};
},
emit: function () {
var args = [];
for (var _i = 0; _i < arguments.length; _i++) {
args[_i] = arguments[_i];
}
// take care of user trying to unsub inside a listener
listeners.slice().forEach(function (listener) {
if (listeners.indexOf(listener) > -1) {
listener.apply(void 0, args);
}
});
},
};
}
exports.createEvents = createEvents;
//# sourceMappingURL=index.js.map
```
## License
MIT © [slorber](https://github.com/slorber)
# Hire a freelance expert
Looking for a React/ReactNative freelance expert with more than 5 years production experience?
Contact me from my [website](https://sebastienlorber.com/) or with [Twitter](https://twitter.com/sebastienlorber).