let timerInterval = null;
let timerTimeout = 10;

function setTimerInterval() {
  if (!timerInterval) {
    timerInterval = setInterval(function() {
      postMessage("timerTick");
    }, timerTimeout);
  }
}

function clearTimerInterval() {
  clearInterval(timerInterval);
  timerInterval = null;
}

onmessage = function(event) {
  if ("run_flag" in event.data) {
    if (event.data["run_flag"]) {
      setTimerInterval();
    } else {
      clearTimerInterval();
    }
  } else if ("set_timeout" in event.data) {
    timerTimeout = event.data["set_timeout"];
  }
}