// 例: 変数を隠蔽した書き方
(() => {
  function CountDown() {
    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);
  }
  document.addEventListener("DOMContentLoaded", CountDown, false);
})();