Update: This page was originally published on April 24, 2012. Update was to added the code highlighter and make it readalbe
This is my rewrite of John Resig's Simple Javascript Inheritance. I tried to make things a bit simple, and use different variable names for clear understanding. The identifier "Class" was used used too often to throw me in vicious circle of trying to understand what it is doing. Later I understood the prototype chain.

All I learnt from:

• http://coffeescript.org/#classes 
• http://yehudakatz.com/2011/08/12/understanding-prototypes-in-javascript/
• http://mckoss.com/jscript/object.htm 

This looks interesting, I will look at this in my free time: http://javascriptweblog.wordpress.com/2010/06/07/understanding-javascript-prototypes/

let Class1 = function(){}; Class1.extend=function(obj){ // A lot is achieved in this line. Prototypal inheritance in action var tempproto = Object.create(this.prototype); for(var prop in obj){ if(obj.hasOwnProperty(prop)){ tempproto[prop] = obj[prop]; } } function Class() { // console.log('in Class ()'); if (obj.init) obj.init.apply(this,arguments); } //prototype of Class object assume this is called by Person.extent tempproto['_super']=this.prototype; //then this.prototype is Person's prototype object Class.prototype = tempproto; Class.prototype.constructor = Class; Class.extend = Class1.extend; // arguments.callee; //Class['_super']=this.prototype; return Class; }; var Person = Class1.extend({ init: function(isDancing){ this.dancing = isDancing; }, dance: function(){ return this.dancing; } }); var Ninja = Person.extend({ // dancing: true, // this will overwrite the _super.dancing but it wont // affect Person init: function(){ this._super.init( false ); // or this._super.dancing = false; // this.dancing = true; }, // This whole dance function can be commented, still superninja // will have dance function dance: function(){ // Call the inherited version of dance() return this._super.dance(); }, swingSword: function(){ return true; } }); var SuperNinja = Ninja.extend({ }) var Sam = Person.extend({ }) function fn() { let p = new Person(true); console.log('p.dance():' + p.dance()); // => true let n = new Ninja(); console.log('n.dance():' + n.dance()); // => false console.log('n.swingSword():' + n.swingSword()); // => true let sam = new Sam(true); console.log('Sam.dance():' + sam.dance()); // => false console.log('Sam.swingSword():' + sam.swingSword); // => undefined let s = new SuperNinja(true); console.log('SuperNinja s.dance():' + s.dance()); // => false console.log('SuperNinja s.swingSword():' + s.swingSword()); // => true } fn();

This is how the class looks like in firebug