Example of prototype inheritance in JavaScript

prototype-inheritance.js

// 'super' with prototype inheritance

function A() {}
A.prototype.say = function(m) { console.log('A: ' + m); };

function B() {}
B.prototype = new A();
B.prototype.say = function(m) {
  this.constructor.prototype.say(m);
  console.log('\nB: ' + m);
};

new B().say('hello'); // => A: hello\nB: hello

// --- constructor:

function Foo(x) { this.x = x; }

function Bar(x, y) {
  Foo.call(this, x);
  this.y = y;
}
Bar.prototype = new Foo();
new Bar(1, 2).x // => 1