StopWatch created by iamwill123 - https://repl.it/I9AY/0

StopWatch.js

// create a stop watch

function makeStopWatch() {
  var seconds = 0;
  var intervalID;
  
  function tickTock() {
    console.log(seconds);
    return seconds++;
  }
  function startWatch() {
    // function to start our watch
    console.log(intervalID);
    intervalID = setInterval(tickTock, 1000);
  }
  function stopWatch() {
    // function to stop our watch
    clearInterval(intervalID);
  }
  return {
    start: startWatch,
    stop: stopWatch
  }
}
var appleWatch = makeStopWatch();

appleWatch.start(); // fire it off

setTimeout(function() {
  appleWatch.stop();
}, 9000); // stop after 8 seconds