moop.js

// Extend class
function extend (proto) {
  var Super = this;
    var ctor;

    if (proto.hasOwnProperty('constructor')) {
        ctor = proto.constructor;
    } else {
        ctor = function () {
            Super.apply(this, arguments);
        };
    }

    Object.setPrototypeOf(ctor.prototype, this.prototype);

    // Copy static methods and properties.
    Object.getOwnPropertyNames(Super).forEach((name) => {
        if (['arguments', 'length', 'name', 'caller', 'prototype'].indexOf(name) > -1) {
            return;
        }

        Object.defineProperty(
          ctor,
          name,
          Object.getOwnPropertyDescriptor(Super, name)
        );
    });

    // Copy prototype methods and properties.
    Object.getOwnPropertyNames(proto).forEach((name) => {
        if (name === 'constructor') {
            return;
        }
        
        Object.defineProperty(
          ctor.prototype,
          name,
          Object.getOwnPropertyDescriptor(proto, name)
        );
    });

    return ctor;
}

// Static new
function new_() {
    var instance = Object.create(this.prototype);
    this.apply(instance, arguments);
    return instance;
};

// Basic type
function Type() {}
Type.extend = extend;
Type.new = new_;

// Implement interface (copy methods)
function interface(target, source) {
	Array.prototype.concat.apply([], arguments).slice(1).forEach(
    function(source) {
      if (typeof source !== 'function') {
        return;
      }
      
      var proto = source.prototype;
      Object.getOwnPropertyNames(proto).forEach(function(name){
				var value = proto[name];
        if (name === 'constructor') {
        	return;
        }
        
        if (typeof value === 'function') {
        	target.prototype[name] = value;
        }
      });
    }
  );
}

// Check if class implements interface (has exactly the same methods). 
function implements(target, source) {
	var match = true;
  
	Object.getOwnPropertyNames(source.prototype).forEach(function(name){
  	var value = source.prototype[name];
    if (name === 'constructor') {
      return;
    }
        
    if (typeof value === 'function') {
    	if (! target.prototype.hasOwnProperty(name) || target.prototype[name] !== value) {
	      match = false;
      }
    };
  });
  
  return match;
}