Prototyping example

prototyping_basic.js

function Engineer () {}

Engineer.prototype = {
  getYearsWorked: function () { 
    return this.yearsWorked;
  }
};

function UIEngineer (years) {
  this.yearsWorked = years;
}

UIEngineer.prototype = new Engineer();

var x = new UIEngineer(5)

x.getYearsWorked();
//>>> 5
if (x instanceof Engineer) console.log("Is Engineer!");
//>>> Is Engineer!
if (x instanceof UIEngineer) console.log("Is UI Engineer!");
//>>> Is UI Engineer!