// 例: 変数の隠蔽化
var count = 10, tmID, infobox = document.getElementById("timeout");
function countDown() {
  if (--count == 0) {
    infobox.innerHTML = "ぼかーん";
  } else {
    infobox.innerHTML = count + "秒前";
    tmID = setTimeout(countDown, 1000);
  }
}
function startCountDown() {
  tmID = setTimeout(countDown, 1000);
  infobox.removeEventListener("click", startCountDown, false);
  infobox.addEventListener("click", stopCountDown, false);
}
function stopCountDown() {
  clearTimeout(tmID);
  infobox.innerHTML = "停めました。";
  infobox.removeEventListener("click", stopCountDown, false);
}
infobox.addEventListener("click", startCountDown, false);