tiny-typed-emitter

    2.1.0 • Public • Published

    tiny-typed-emitter

    Have your events and their listeners type-checked with no overhead.

    npm version

    Install

    Simply add the dependency using npm:

    $ npm i tiny-typed-emitter

    or using yarn:

    $ yarn add tiny-typed-emitter

    Usage

    1. import tiny-typed-emitter library:
    import { TypedEmitter } from 'tiny-typed-emitter';
    1. define events and their listener signatures (note: quotes around event names are not mandatory):
    interface MyClassEvents {
      'added': (el: string, wasNew: boolean) => void;
      'deleted': (deletedCount: number) => void;
    }
    1. on this step depending on your use case, you can:
    • define your custom class extending EventEmitter:
      class MyClass extends TypedEmitter<MyClassEvents> {
        constructor() {
          super();
        }
      }
    • create new event emitter instance:
      const emitter = new TypedEmitter<MyClassEvent>();

    Generic events interface

    To use with generic events interface:

    interface MyClassEvents<T> {
      'added': (el: T, wasNew: boolean) => void;
    }
    
    class MyClass<T> extends TypedEmitter<MyClassEvents<T>> {
    
    }

    Compatible subclasses with different events

    The type of eventNames() is a superset of the actual event names to make subclasses of a TypedEmitter that introduce different events type compatible. For example the following is possible:

    class Animal<E extends ListenerSignature<E>=ListenerSignature<unknown>> extends TypedEmitter<{spawn: () => void} & E> {
      constructor() {
        super();
      }
    }
    
    class Frog<E extends ListenerSignature<E>> extends Animal<{jump: () => void} & E> {
    }
    
    class Bird<E extends ListenerSignature<E>> extends Animal<{fly: () => void} & E> {
    }
    
    const animals: Animal[] = [new Frog(), new Bird()];

    No Overhead

    Library adds no overhead. All it does is it simply reexports renamed EventEmitter with customized typings. You can check lib/index.js to see the exported code.

    Install

    npm i tiny-typed-emitter

    DownloadsWeekly Downloads

    35,094

    Version

    2.1.0

    License

    MIT

    Unpacked Size

    5.3 kB

    Total Files

    5

    Last publish

    Collaborators

    • binier