instanceof vs Object.prototype.toString

instanceof vs Object.prototype.toString

!function () {

  // helper to set prototype chain up
  var Constructor = function () {};
  Constructor.prototype = Array.prototype;
  
  var NotRealArray = function () {};
  // inherit from Array
  NotRealArray.prototype = new Constructor;

  // create an instance
  var notRealArray = new NotRealArray;
  
  // instanceof
  console.log( notRealArray instanceof Array ); // prints true, since instanceof just looks for "constructor" property in prototype chain

  // Object.prototype.toString
  console.log( ({}).toString.call( notRealArray ).indexOf('Array') !== -1 ); // prints false, ({}).toString.call() returns "[object Object]" here

}();