Quick and dirty summary of prototypical inheritance in JS

inherit.js

// Create a Car object with doors.
function Car() {
	this.doors = 4;
};

// Method to return model year.
Car.prototype.getYear = function(n) {
	var num = typeof(n) == 'undefined' ? 1 : n;
	return 2001 + num;
};


// Hyundai class inherits from Car using standard prototypical inheritance.
function hyundai(){}
hyundai.prototype = new Car();
hyundai.color = 'red';

// Since inheritance created new object instance, we can access value set in constructor.
console.log('Hyundai doors: ' + hyundai.prototype.doors);	
console.log('Hyundai color: ' + hyundai.color);
console.log('Hyundai year: ' + hyundai.prototype.getYear() + '\n');

// Tesla class inherets using Node.js style prototypical inheritance.
function tesla(){}
tesla.prototype.__proto__ = Car.prototype;
tesla.color = 'blue';

// Since object not instantiated with inheritance, no access to values set in constructor.
console.log('Tesla doors: ' + tesla.prototype.doors);
console.log('Tesla color: ' + tesla.color);	
console.log('Tesla year: ' + (tesla.prototype.getYear(10)));

/*
Outputs:

Hyundai doors: 4
Hyundai color: red
Hyundai year: 2002

Tesla doors: undefined
Tesla color: blue
Tesla year: 2011
*/