using VanillaJS syntax (prototypes) vs ES6 Syntax for class definition - Node.js Object

Node.js examples for Object:Class in ES6

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Description

using VanillaJS syntax (prototypes) vs ES6 Syntax for class definition

Demo Code

// //from ww  w.  ja v  a  2s .  co  m
function EventEmitter() {
    this._callbacks = {};

    EventEmitter.prototype._initializeEvent = function (eventName) {
    if (typeof this._callbacks[eventName] == 'undefined') {
        this._callbacks[eventName] = [];
    }
}

EventEmitter.prototype.on = function (eventName, callback) {
    this._initializeEvent(eventName);
    this._callbacks[eventName].push(callback);
}

EventEmitter.prototype.emit = function (eventName, data) {
    this._initializeEvent(eventName);
    for (let i = 0; i < this._callbacks[eventName].length; i++) {
        this._callbacks[eventName][i](data);
    }
}
}

// using ES6 syntax (classes)
class EventEmitterES6 {
    constructor() {
        this._callbacks = {}
    }

    _initializeEvent(eventName) {
        if (typeof this._callbacks[eventName] == 'undefined') {
            this._callbacks[eventName] = [];
        }
    }

    on(eventName, callback) {
        this._initializeEvent(eventName);
        this._callbacks[eventName].push(callback);
    }

    emit(eventName, data) {
        this._initializeEvent(eventName);
        this._callbacks[eventName].map(x => x(data));
    }
}

let emitter = new EventEmitter();
emitter.on('print', console.log);
emitter.on('print', (x) => console.log(x + " " + x));
emitter.emit('print', 'Hello world');

let emitterES6 = new EventEmitterES6();
emitterES6.on('print', console.log);
emitterES6.emit('print', 'Hello world from ES6');

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