JS Ошибка при сокрытии элемента

var date = new Date(); 
var trueTime = date.getTime(); 
 
function check() { 
  if ((localStorage.getItem("timeToUnblock")) & trueTime < localStorage.getItem('timeToUnblock')) { 
  document.getElementById("RegisterButton").style.visibility ="hidden"; 
alert("wait"); 
  } else if (!(localStorage.getItem("timeToUnblock"))){ 
 
 } else{ 
    alert("block time is end!");  
 } 
}

<script>check();</script> 
<div id="RegisterButton"> 
<input type="button" value="Кнопка" onclick="timeCounter()" >//onclick- сохраняет время 
</div>