如何在选中复选框时打开div？

<input type="checkbox" id="checkbox">
<div id="content" style="display: none;">这是需要显示/隐藏的内容</div>

var checkbox = document.getElementById("checkbox");
var content = document.getElementById("content");

checkbox.addEventListener("change", function() {
  if (checkbox.checked) {
    content.style.display = "block";
  } else {
    content.style.display = "none";
  }
});