Traffic Light Function drill

index.js

function doTrafficLights() {
  const activeLight = getActiveLight();
  if (activeLight === 'red') {
    turnRed();
  }
  else if (activeLight === 'green') {
    turnGreen();
  }
  else {
    turnYellow();
  }
}

// this function randomly returns red, yellow, or green
// and is called by doTrafficLights.
// don't modify it!
function getActiveLight() {
  return (['red', 'green', 'yellow'])[Math.floor(Math.random() * 3)];
}

/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

function turnOffLights() {
  $('.traffic-light').removeClass('yellow-on red-on green-on');
}

function turnGreen() {
  turnOffLights();
  $('.green-light').addClass('green-on');
}

function turnYellow() {
  turnOffLights();
  $('.yellow-light').addClass('yellow-on');
}

function turnRed() {
  turnOffLights();
  $('.red-light').addClass('red-on');
}


function handleClicks() {
  $('.js-control-lights').click(function() {
    doTrafficLights();
  });
}

$(function() {
  turnOffLights();
  handleClicks();
});

https://repl.it/@liseferguson/Traffic-lights-drill