event-maker

Very simple event emitter.

Feature

• A single event object per an event
• Tiny code base - less 1kb
• Written by TypeScript

Install

Install with npm:

npm i @ncukondo/event-maker

Requirement: ECMAScript 2015 because this library use Map.

Usage

Create an event object and register handler and invoke handlers.

import { makeEvent } from "@ncukondo/event-maker";

const onEvent1 = makeEvent();
// Register a handler
onEvent1(() => {
  console.log(1);
});
// Register an once only handler
onEvent1.once(() => {
  console.log(2);
});
// Invoke handler
onEvent1.emit(); // 1,2
onEvent1.emit(); // 1
// Unregister handler
onEvent1.clear();

You can pass payload to the event.

const onEvent2 = makeEvent<{ payload: string }>();
// Register handler
onEvent2((value) => {
  console.log(1, value.payload);
});
onEvent2((value) => {
  console.log(2, value.payload);
});
// Invoke handler
onEvent2.emit({
  payload: "value"  //1 value, 2 value
});
// Unregister handler
onEvent2.clear();

You also can pass multiple paramaters to the event.

const onEvent3 = makeEvent<[type:string,message:string]>();
// Register handler
onEvent3((type,message) => {
  console.log(1, `eventType:${type} message:${message}`);
});
// Invoke handler
onEvent3.emit("customEvent1","some message"); // eventType:customEvent1 message:some message
// Unregister handler
onEvent3.clear();

API

declare type ToArgsType<T> = T extends Array<unknown> ? T : readonly [T];
declare type EventHandler<T> = (...args: ToArgsType<T>) => unknown;
declare type Eventemitter<T> = {
    /**
     * Register an event handler
     */
    (handler: EventHandler<T>): void;
    /**
     * Register an once only event handler
     */
    once: (handler: EventHandler<T>) => void;
    /**
     * Remove an event handler
     */
    remove: (handler: EventHandler<T>) => void;
    /**
     * Remove all event handlers
     */
    clear: () => void;
    /**
     * Invoke all handlers
     */
    emit: (...value: ToArgsType<T>) => void;
};
declare const makeEvent: <T extends unknown = []>() => Eventemitter<T>;
export { makeEvent };
export type { EventHandler, Eventemitter };

Changelog

See Releases page.

Running tests

Install devDependencies and Run npm test:

npm test

Author

• github/ncukondo

License

MIT

Related

• eventmit: A single event object per the event.
• developit/mitt: 🥊 Tiny 200 byte functional event emitter / pubsub.
  • Support multiple event type