Prototyping Array to inherit from EventEmitter in Node.js

Question

Prototyping Array to inherit from EventEmitter in Node.js

Am currently working on a project where I require to inherit from EventEmitter. I need an array to emit events on certain cases, say, when some length has been exceeded.

I used this snippet:

var events = require('events');
Array.prototype.__proto__ = events.EventEmitter.prototype;

It works fine, but it is said it is anti-pattern.

In another question, it is suggested to use:

util.inherits(Array, events.EventEmitter.prototype);

But it does NOT work. So what is the right way to do this?

javascript
arrays
node.js
prototype
eventemitter

Answer 1

The problem here is, that this will change all Arrays in your application and not only one. In this situation it would be better to use a new Type that extends from EventEmitter and delegates to an Array.

i.e.

// Create a new object that ...
function MyEventArray() {
    // ...owns an Array as property...
    this.array = new Array();
}

// ... and extends from EventEmitter...
MyEventArray.prototype = Object.create(EventEmitter.prototype);
MyEventArray.prototype.constructor = MyEventArray;

// ... and has functions that delegate to the array.
MyEventArray.prototype.push(obj) {
    this.array.push(obj);
}
...


// This object is an EventEmitter and can be used like an Array:
var myArray = new MyEventArray();
myArray.push(someStuff);