constructor_with_type.js

const introduce = function() {
  console.log("Hi! I'm " + this.name + ". My job is " + this.job + ".");
}

function makeRobot(name, job) {
  return {
    name: name,
    job: job,
    
    introduce,
    _isRobotInstance: true
  };
}

var bender = makeRobot("Bender", "bending");
bender.introduce();   // Hi! I'm Bender. My job is bending.
if(bender._isRobotInstance){
  console.log("Bender is a Robot");
}

var wallE = makeRobot("Wall-E", "trash collection");
wallE.introduce();    // Hi! I'm Wall-E. My job is trash collection.
if(wallE._isRobotInstance){
  console.log("wallE is a Robot");
}