如何添加CheckAll按钮

<input type="checkbox" id="checkAll">
<label for="checkAll">Check All</label>

var checkAllBtn = document.getElementById('checkAll');
var checkboxes = document.querySelectorAll('input[type="checkbox"]');

checkAllBtn.addEventListener('click', function() {
  checkboxes.forEach(function(checkbox) {
    checkbox.checked = checkAllBtn.checked;
  });
});

label {
  display: inline-block;
  margin-bottom: 10px;
  cursor: pointer;
}

input[type="checkbox"] {
  display: none;
}

input[type="checkbox"] + label:before {
  content: "";
  display: inline-block;
  vertical-align: middle;
  width: 16px;
  height: 16px;
  margin-right: 5px;
  border: 1px solid #ccc;
  background-color: #fff;
}

input[type="checkbox"]:checked + label:before {
  background-color: #2196f3;
}