JS.Class - Ruby-like classes for JavaScript

Type-checking and the class tree

All objects created from JS.Class classes have a klass property that refers to the class it belongs to. You can use this for type-checking and for accessing static methods on the class. Objects also have an isA() method that can be used to type-check against the whole class tree.

        /**
         * These classes exist...
         * var Animal = JS.Class({...});
         * var Dog = JS.Class(Animal, {...});
         * var Table = JS.Class({...});
         */
        
        var rex = new Dog('rex');
        rex.isA(Dog)      // -> true
        rex.isA(Animal)   // -> true
        rex.isA(Object)   // -> true
        rex.isA(Table)    // -> false

All classes have a superclass property that refers to their parent class, or Object if they have no parent class.

        rex.klass               // -> Dog
        rex.klass.superclass    // -> Animal

You can use this from within methods to access class constructors, static methods, etc…

        var Sheep = new JS.Class(Animal, {
          // Returns a new Animal with the same name as the sheep
          clone: function() {
            return new this.klass.superclass(this.name);
          }
        });

Each class also has a subclasses property, which contains an array of its subclasses. This is less useful for programming, but is used to allow static methods to be inherited.

JS.Class Ruby-like classes for JavaScript

Type-checking and the class tree