Javascript/innerText

var a = 0;
function s1Func(){
  var s1Div = document.getElementById("s1Div");
  s1Div.innerText += a++;
}
	

var s2Btn = document.getElementById("s2Btn");
s2Btn.onclick = function s2Func(){
  var d = new Date();
  var year = d.getFullYear();
  var month = d.getMonth() + 1;
  var week = d.getDay();
  var day = d.getDate();
  var dayOfTheWeek = [
	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
  	];
  var hour = d.getHours();
  var minute = d.getMinutes();
  var second = d.getSeconds();
  var today = document.createElement("div");
  today.innerText = year + "年" + month + "月" + day + "日 " + dayOfTheWeek[week];
  s2Btn.after(today);
  var time = document.createElement("div");
  time.innerText = hour + "時" + minute + "分" + second + "秒";
  today.after(time);
}