polymorphism

This is a very small node.js module which adds a non-enumerable extend property to Function.prototype. The extend property is a function which creates a prototype for the function it is called on using a function which is passed to it. The created prototype is automatically attached to the function which extend is called on. In order to remain compatible with node's util.inherits it also creates a property super_ on the function it was called on pointing at the function which was passed to it. It works out of the box in both node.js and browserify.

Installation

npm i polymorphism

Usage

The following works in both node.js and browserify:

require('polymorphism'); // No need to save the value, a non-enumerable property is added to `Function.prototype`
 
// Define Constructors
var Parent = function (data) {
  this.data = data;
};
var Child = function (data) {
  Child.super_.call(this, data); // Call super constructor passing in data
};
 
// Important: this overwrites the prototype. Make sure you make this call before defining any methods.
Child.extend(Parent);
 
// Define method for child.
Child.prototype.logData = function () {
  console.log(this.data);
};
 
// Do stuff
var c = new Child('foo');
console.log(c instanceof Child); // true
console.log(c instanceof Parent); // true
c.logData(); // 'foo'

Differences from Other Modules

Much like the inherits module this module is meant to be used with both node.js and browserify so you don't have to export node's entire util module module to the browser when sharing code between the server and browser. Unlike the inherits module and the util.inherits function this module defines its functionality as a non-enumerable property on Function.prototype (more information here).

Compatibility

This module assumes the existence of Object.create and Object.defineProperty. This means that it will work with node.js and the following browsers:

IE	Chrome	Firefox	Safari	Opera
9+	5+	4+	5+	12+

License

The MIT License

Copyright (c) 2014 Kenneth Powers

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.