Javascript/五秒当て

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START

五秒あて

javascript
window.onload = function(){
  var isStarted = false;
  var startTime;
  var stop;
  var result = document.getElementById("result");
  var btn = document.getElementById("btn");
  var resultP = document.getElementById("resultP");
  var evaluation = document.getElementById("evaluation");

  btn.addEventListener("click", function(){
  	if(!isStarted){
  	  isStarted = true;
  	  this.innerHTML = "STOP";
  	  startTime = new Date();
  	  resultP.innerHTML = "";
  	  evaluation.innerHTML = "計測中";
	} else {
  	  isStarted = false;
  	  this.innerHTML = "START";
  	  stop = (new Date() - startTime) / 1000;
  	  result.innerHTML = stop.toFixed(2);
  	  var substraction = 5 - stop;
  	  substraction = substraction.toFixed(2);
  	  if(substraction < 0){
  	  	substraction = Math.abs(substraction);
  	  	resultP.innerHTML = substraction + "秒遅い";
  	  } else {
  	  	resultP.innerHTML = substraction + "秒早い";
  	  }
  	  if(stop>4.9 && stop<5.1){
  	  	evaluation.innerHTML = "Perfect";
  	  } else if(stop>4.5 && stop<5.5){
  	  	evaluation.innerHTML = "Good";
  	  } else {
  	  	evaluation.innerHTML = "Bad";
  	  }
  	}
  });
};