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Emitter

import { Emitter } from '@dr.pogodin/react-utils';

Emitter class implements a simple listeneable data emitter.

Example
const emitter = new Emitter();
const unsubscribe = emitter.addListener(console.log);
emitter.emit('Hello World!'); // Console output: Hello World!
unsubscribe(); // Disconnects the listener from the emitter.
emitter.emit('Are you listening?'); // Console outputs nothing.
info

The Emitter source code has been moved to JS Utils library, and it is re-exported from there; thus, it also can be imported as

import { Emitter } from '@dr.pogodin/js-utils';

Fields​

  • .hasListeners — boolean — true if any listener is connected to the emitter; false otherwise.
  • .listeners — function[] — Array of listeners connected to the emitter. Although accessible for direct manipulations, addListener() and removeListener() methods should be preferred to add/remove listeners in most cases.

Methods​

constructor()​

const emitter = new Emitter();

Creates a new emitter with no listeners connected.

addListener()​

emitter.addListener(listener: function): function;

Connects given listener to the emitter, or does nothing if it is already connected. Each connected listener will be called once on each subsequent emit() call with the arguments passed into emit().

This method returns a function which can be triggered with no arguments to unsubscribe listener from the emitter. It is just an auxiliary wrapper around removeListener() method, which can be used alternatively.

emit()​

emitter.emit(...args: any);

Calls every connected listener once with the given arguments.

removeAllListeners()​

emitter.removeAllListeners()

Diconnects all listeners from the emitter.

removeListener()​

emitter.removeListener(listener: function);

Disconnects given listener from the emitter, or does nothing if it is not connected to it.