copy_property.js

'use strict';

var slice = Array.prototype.slice,
    copyProperty;

copyProperty = function () {
    var properties = slice.call(arguments),
        to         = properties.pop(),
        from       = properties.pop(),
        i, length, property, descriptor;
    for (i = 0, length = properties.length; i < length; i++) {
        property   = properties[i];
        descriptor = Object.getOwnPropertyDescriptor(from, property);
        Object.defineProperty(to, property, descriptor);
    }
};

module.exports = copyProperty;

extend.js

'use strict';

var copyProperty = require('./copy_property'),
    extend;

extend = function (Child, Parent) {
    var properties = Object.keys(Parent).concat(Parent, Child),
        Class;
    copyProperty.apply(null, properties);
    Class = function () {
        this.constructor = Child;
    };
    Class.prototype = Parent.prototype;
    Child.prototype = new Class;
    Child._super    = Parent.prototype;
    return Child;
};

module.exports = extend;

subclass.js

'use strict';

var extend = require('./extend'),
    subclass;

subclass = function (Parent, constructor) {
    var Child;
    if (constructor == null) {
        Child = function () {
            return Child._super.constructor.apply(this, arguments);
        };
    }
    else {
        Child = function () {
            Child._super.constructor.apply(this, arguments);
            return constructor.apply(this, arguments);
        };
    }
    extend(Child, Parent);
    return Child;
};

module.exports = subclass;