modify-event

Modify the value of the specific object's event

const {EventEmitter} = require('events');
const modifyEvent = require('modify-event');

const emitter = new EventEmitter();

modifyEvent(emitter, 'foo', val => val * 2);

emitter.on('foo', data => {
  data; //=> 2
});

emitter.emit('foo', 1);

Installation

Use npm.

npm install modify-event

API

const modifyEvent = require('modify-event');

modifyEvent(eventEmitter, eventName, modifier)

eventEmitter: EventEmitter
eventName: string symbol (event name)
modifier: Function
Return: EventEmitter (a reference to the first argument)
It changes the first argument of the event listeners for a given event, in response to the return value of the modifier function.

const {EventEmitter} = require('events');
const modifyEvent = require('modify-event');

const emitter = new EventEmitter();
const eventName = Symbol('custom event name');

modifyEvent(emitter, eventName, val => `${val}b`);
modifyEvent(emitter, eventName, val => `${val}c`);

emitter
.on(eventName, listener)
.emit(eventName, 'a');

function listener(data) {
  data; //=> 'abc'
}

License

Copyright (c) 2015 - 2019 Shinnosuke Watanabe
Licensed under the MIT License.