Klassy

A bare bones vanilla js implementation of classes, influenced by coffeescript.

Why?

ES6 has classes, coffeescript and typescript have classes..

Well, for many reasons this may still be useful

Maybe your team would like to move to ES6 soon, but cannot due to browser concerns
or you cannot/do not want to transpile
or your team uses ES6 but only certain features
or you're concerned about ES6 performance
or you just really like ES5...

Either way, this provides a pretty consistent way to define classes in JS so that when the time comes to switch to ES6, or coffeescript, or typescript, it will be fairly easy to change and will not require refactoring code (much).

Features

Constructors

Simply pass a method in with the name constructor and it will behave as a constructor.

var Person = klassy({
  name: "Person",
  constructor: function(name) {
    if (name) {
      this.name = name;
    }    
  }
});

var bill = new Person('Bill');
var person = new Person();
bill.name // Bill
person.name // Person

Static Methods

Any method name beginning with $ will be saved as a static method. This varies from coffeescipt's @ because the @ is not a valid identifier and would need to be wrapped in quotes to be used. Only $ and _ are valid nonalphanumeric identifiers and _ is conventional for private methods/variables.

var Person = klassy({
  constructor: function(name) {
    this.name = name;
  },
  $talk: function() {
    return "Hi!";
  }
}
});

Person.talk() // Hi!

var bill = new Person('Bill');
bill.talk() // womp womp

Subclassing

Subclassing multilple klasses is supported.

var Animal = klassy({
  $say: function() {
    return "I'm an animal";
  }
});

var Dog = Animal.extend({
  constructor: function(breed) {
    this.breed = breed;
  },
  getBreed: function() {
    return this.breed;
  }
});

var Bulldog = Dog.extend({
  constructor: function() {
    this.breed = "Bulldog";
  }
});

var george = new Bulldog("George");
george.getBreed() // Bulldog
Bulldog.say() // I'm an animal

Super

Call the super class' method with super, with the first argument being the method you are looking to access, and the rest being the arguments you want to pass it. NOTE: Super was done this way to avoid expensive wrappers for every method of every class, and also to avoid using function.caller as it is not in the official spec and does not work in strict mode. This method searches up the prototype chain and invokes the super class' method with the subclasses context (this);

var Animal = klassy({
  constructor: function(name) {
    this.name = name;
  },
  getName: function(surname) {
    return surname + " " + this.name;
  }
});

var Dog = Animal.extend();

var Bulldog = Dog.extend({
  getName: function() {
    // do some stuff
    return this.super("getName", "Mr.");
  }
});

var george = new Bulldog("George");
george.getName(); // George

Testing

You will need to install grunt-cli if you haven't already. Run grunt test to run tests and coverage. Coverage is saved in coverage folder.

scttdavs / klassy