Add inheritance in javascript

Good read: Inheritance and the prototype chain

https://goo.gl/Im9q4k

object_oriented_javascript/playlist/media.js

@@ -0,0 +1,13 @@
+function Media(title, duration) {
+  this.title = title;
+  this.duration = duration;
+  this.isPlaying = false;
+}
+
+Media.prototype.play = function() {
+  this.isPlaying = true;
+};
+
+Media.prototype.stop = function() {
+  this.isPlaying = false;
+};

object_oriented_javascript/playlist/song.js

@@ -1,17 +1,9 @@
 function Song(title, artist, duration) {
-  this.title = title;
+  Media.call(this, title, duration);
   this.artist = artist;
-  this.duration = duration;
-  this.isPlaying = false;
 }
 
-Song.prototype.play = function() {
-  this.isPlaying = true;
-};
-
-Song.prototype.stop = function() {
-  this.isPlaying = false;
-};
+Song.prototype = Object.create(Media.prototype);
 
 Song.prototype.toHTML = function() {
   var htmlString = '<li';