function startTimer() {
  counterStart = counter;
  setState(states.count);
  countDown();
  if (!counterInterval)
    counterInterval = setInterval(countDown, 1000);
}
// start or restart timer => state: count
start or restart timer => state: count
start or restart timer = > state : count
function startTimer() {
  counterStart = counter;
  setState(states.count);
  countDown();
  if (!counterInterval)
    counterInterval = setInterval(countDown, 1000);
}
function startTimer ( ) { counterStart = counter ; setState ( states . count ) ; countDown ( ) ; if ( ! counterInterval ) counterInterval = setInterval ( countDown , 1000 ) ; }
start or restart timer => state: count
start or restart timer = > state : count