In.js : prototypal inheritance done right

In comes from Inheritance because this is what the lib addresses. More accurately, it simplifies prototypal inheritance. In.js is under MIT license.

It is minimal by design and it takes care of some details often overlooked:

• the constructor of an instance of T points to the function T, as expected

function Base() {}
Base.prototype.K = 0;

//Bad free style
function Sub() {}
Sub.prototype = new Base();
var s = new Sub();
s.K === 0; //true
s.constructor === Sub; //false

//With In.js
function Sub2() {}
In.inheritFrom(Sub2, Base);
s.K === 0; //true
s.constructor === Sub2; //true

• it provides a zuper member with which to access the parent class and constructor

function Base(x) { this.x = x; }
function Sub(x) { this.zuper(x); }
In.inheritFrom(Sub, Base);
var s = new Sub(2);
s.x === 2; //true

• the In.inheritFrom(...) method can be called at any point of the class definition. Just after the Ctor definition, after the last member definition or at any point in between.

function Base() {}
function Sub() {}
Sub.prototype.Y = 1; //not overwritten by the following call
In.inheritFrom(Sub, Base);
Sub.prototype.Z = 2; //not ignored when done after inheriting

var s = new Sub();
s.Y === 1; //true
s.Z === 2; //true

• ... and it performs checks like avoiding the repeated inheritance of the same class

Docs and examples

Documentation is available here.

The spec file contains some examples of use. A coverage report is available too.

How do I get set up?

• How to use the lib (basic)
  • copy js/src/In.js in your project
  • add it to your HTML in a script tag. The module will be attached to window.In
• How to use the lib (advanced)
  • The lib is a Bower component. You can add it to your dependencies in this way:

  "dependencies": {
      "in_js": "git+https://github.com/valentinomiazzo/in_js.git"
  }

  • The lib is a Require.js module. Remember to add it to your require.config()
• How to modify the lib, run tests, etc...
  • Prerequisites
    • install Node.js
    • install Npm
    • npm install grunt-cli -g
    • npm install bower -g
  • Install
    • clone this repository
    • in the root of the cloned repo, type (on Windows you may need to disable antivirus if you get strange issues during the install):
    • npm install
    • On some platforms you may need to install apt-get install nodejs-legacy if the command above doesn't work.
  • Build
    • grunt
    • docs are generated in build/docs
  • Test
    • Jasmine it is used for testing.
    • tests are in js/spec
    • tests reports are in build/tests
    • coverage reports are in build/coverage

Contribution guidelines

• For pull requests
  • go here
• For issues
  • go here