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

chaining prototype methods

function Shape(){//from  ww  w.j a  v a  2  s .  co  m
   this.isDrawable = true;
}
Shape.prototype.getDrawable = function(){
   return this.isDrawable;
};

function Rectangle(){
   this.hasFourEdges = false;
}

//inherit from Shape
Rectangle.prototype = new Shape();

Rectangle.prototype.getFourEdges = function (){
   return this.hasFourEdges;
};

var instance = new Rectangle();
console.log(instance.getDrawable());   //true

prototype chain in javascript

{
    prop: "some value",
    __proto__: {
        foo: "bar",
        constructor: ƒ doSomething(),
        __proto__: {
            constructor: ƒ Object(),
            hasOwnProperty: ƒ hasOwnProperty(),
            isPrototypeOf: ƒ isPrototypeOf(),
            propertyIsEnumerable: ƒ propertyIsEnumerable(),
            toLocaleString: ƒ toLocaleString(),
            toString: ƒ toString(),
            valueOf: ƒ valueOf()
        }
    }
}