var what = function(obj) {

  return obj.toString().match(/ (\w+)/)[1];

};

​

var p;

​

// Normal obj with constructor.

function Entity() {}

p = new Entity();

console.log("constructor:", what(p.constructor), "name:", p.constructor.name , "class:", what(p));

​

// Obj with prototype overriden.

function Player() { console.warn('Player constructor called.'); }

Player.prototype = new Entity();

p = new Player();

console.log("constructor:", what(p.constructor), "name:", p.constructor.name, "class:", what(p));

​

// Obj with constructor property overriden.

function OtherPlayer() { console.warn('OtherPlayer constructor called.'); }

OtherPlayer.constructor = new Player();

p = new OtherPlayer();

console.log("constructor:", what(p.constructor), "name:", p.constructor.name, "class:", what(p));

​

// Anonymous function obj.

p = new Function("");

console.log("constructor:", what(p.constructor), "name:", p.constructor.name, "class:", what(p));

​

// No constructor here.

p = {};

console.log("constructor:", what(p.constructor), "name:", p.constructor.name, "class:", what(p));

​

// ES6 class.

class NPC { 

  constructor() {

  }

}

p = new NPC();

console.log("constructor:", what(p.constructor), "name:", p.constructor.name , "class:", what(p));

​

// ES6 class extended

class Boss extends NPC {

  constructor() {

    super();

  }

}

p = new Boss();

console.log("constructor:", what(p.constructor), "name:", p.constructor.name , "class:", what(p));