CODE EXAMPLE FOR JAVASCRIPT

prototype chain in javascript

var o = {
  a: 2,
  m: function() {
    return this.a + 1;
  }
};

console.log(o.m()); // 3
// When calling o.m in this case, 'this' refers to o

var p = Object.create(o);
// p is an object that inherits from o

p.a = 4; // creates a property 'a' on p
console.log(p.m()); // 5
// when p.m is called, 'this' refers to p.
// So when p inherits the function m of o, 
// 'this.a' means p.a, the property 'a' of p