inherits

What is inherits?

The inherits npm package is a simple utility module that allows you to implement inheritance in JavaScript. It facilitates the prototype chain linkage between a constructor function (child) and another constructor function (parent) to achieve classical inheritance patterns.

What are inherits's main functionalities?

Inheritance

This code demonstrates how to use the inherits package to set up classical inheritance between a custom constructor MyStream and the built-in EventEmitter constructor. It allows instances of MyStream to inherit methods and properties from EventEmitter.

var inherits = require('inherits');
var EventEmitter = require('events').EventEmitter;

function MyStream() {
  EventEmitter.call(this);
}

inherits(MyStream, EventEmitter);

MyStream.prototype.write = function(data) {
  this.emit('data', data);
};

var stream = new MyStream();
console.log(stream instanceof EventEmitter); // true
console.log(MyStream.super_ === EventEmitter); // true

Other packages similar to inherits

util

The util package is a core Node.js module that provides a variety of utilities including the 'util.inherits' method, which is similar to the 'inherits' package. It allows you to set up inheritance between constructor functions. However, 'util.inherits' does not support ES6 classes and is considered a legacy feature in Node.js.

extend

The extend package is a utility to shallowly extend one object with one or more others. It is similar to inherits in that it is used to extend objects, but it does not set up the prototype chain for classical inheritance. Instead, it copies properties from source objects to a target object.

class-extend

The class-extend package provides helper functions for dealing with inheritance in JavaScript, specifically designed for ES6 classes. It offers a more modern approach compared to inherits, which is more suited for constructor functions rather than ES6 classes.

README

A dead simple way to do inheritance in JS.

var inherits = require("inherits")

function Animal () {
  this.alive = true
}
Animal.prototype.say = function (what) {
  console.log(what)
}

inherits(Dog, Animal)
function Dog () {
  Dog.super.apply(this)
}
Dog.prototype.sniff = function () {
  this.say("sniff sniff")
}
Dog.prototype.bark = function () {
  this.say("woof woof")
}

inherits(Chihuahua, Dog)
function Chihuahua () {
  Chihuahua.super.apply(this)
}
Chihuahua.prototype.bark = function () {
  this.say("yip yip")
}

// also works
function Cat () {
  Cat.super.apply(this)
}
Cat.prototype.hiss = function () {
  this.say("CHSKKSS!!")
}
inherits(Cat, Animal, {
  meow: function () { this.say("miao miao") }
})
Cat.prototype.purr = function () {
  this.say("purr purr")
}


var c = new Chihuahua
assert(c instanceof Chihuahua)
assert(c instanceof Dog)
assert(c instanceof Animal)

The actual function is laughably small. 10-lines small.