parent.js

Javascript inheritance for a 5 years old

Javascript is great, we all know that. Prototypal inheritance is really powerful and some people can do awesome things with that, but let's face it, it has its quirks. Also 99% of the time we only want to create Classes and do simple inheritance. It shouldn't be complicated or prone to errors.

Parent.js is a micro library (less than 30 lines of code), that allows you to create javascript Classes (or in js terminology function constructors) and, at the same time, inherit easily from other Classes.

Use

For using this library, you just need to create your Classes with the following syntax:

var Person = Class({
  // Methods go here...
  ...
}, <BaseClass>)

And this is it! Please keep in mind that <BaseClass> is optional. Not every class needs to inherit! :smirk:. Let's see more examples:

var Person = Class({
  initialize: function (name, surname) {
    this.name = name;
    this.surname = surname;
  },
  sayHi: function () {
    return 'Hi I\'m a Person!!';
  }
});

var Student = Class({
  initialize: function (name, surname, bachelor) {
    this.super.initialize(name, surname);
    this.bachelor = bachelor;
  },
  study: function () {
    return 'I\'m Studying!'
    
  },
  sayHi: function () {
    return 'Hi I\'m a Student!!';
  }
}, Person);

var student = new Student('Jose', 'Vidal', 'Computer Science');

console.dir(student.name, student.bachelor);
// Output: "Jose, Computer Science" 

console.dir(student.sayHi());
// Output: "Hi I'm a Student!" 

console.dir(student.super.sayHi());
// Output: "Hi I'm a Person!" 

console.log(s1 instanceof Student);
// Output: true 
console.log(s1 instanceof Person);
// Output: true 

You can see how the use of parent's methods is trivial with the attribute super from the instances.

Advanced Use

A nice feature is the possibility of creating class methods by prepending __ (two underscores) to the name of the method.

var Person = Class({
  initialize: function (name, surname) {
    this.name = name;
    this.surname = surname;
  },
  __thisIsAClassMethod: function () {
    return 'Hi I\'m a classmethod!';
  },
  thisIsAnInstanceMethod: function () {
    return 'Hi I\'m an instancemethod!';
  }
});

var person = new Person('Jose', 'Vidal');

// Class:
console.log(Person.thisIsAClassMethod());
// Output: 'Hi I\'m a classmethod!'

console.log(Person.thisIsAnInstanceMethod());
// Output: TypeError: undefined is not a function

// Instance:
console.log(person.thisIsAClassMethod());
// Output: TypeError: undefined is not a function

console.log(person.thisIsAnInstanceMethod());
// Output: 'Hi I\'m an instancemethod!'

Installation

bower install parent.js

or

npm install parent.js

Enjoy!

Contribute

Simply make a PR.

Licente

MIT