如何用JS判斷div中內容為空，當為空時隱藏div

<div id="content"></div>
<input type="button" id="btn" value="點擊">
 
var content = document.getElementById("content");
    var btn = document.getElementById("btn");
    btn.onclick = function(){
      if(content.innerText == ''){
        content.style.display = 'none'
      }
 }

content.innerText == ''