如何通过选中复选框来选择列表框的所有元素？

<form>
  <input type="checkbox" onclick="selectAll(this)"> 选择所有
  <br>
  <input type="checkbox" name="option" value="1"> 选项1
  <br>
  <input type="checkbox" name="option" value="2"> 选项2
  <br>
  <input type="checkbox" name="option" value="3"> 选项3
  <br>
  <input type="checkbox" name="option" value="4"> 选项4
  <br>
  <input type="button" value="提交" onclick="submitSelection()">
</form>

function selectAll(source) {
  var checkboxes = document.getElementsByName('option');
  for (var i = 0; i < checkboxes.length; i++) {
    checkboxes[i].checked = source.checked;
  }
}

function submitSelection() {
  var checkboxes = document.getElementsByName('option');
  var selectedItems = [];
  for (var i = 0; i < checkboxes.length; i++) {
    if (checkboxes[i].checked) {
      selectedItems.push(checkboxes[i].value);
    }
  }
  alert("已选择的选项：" + selectedItems.join(', '));
}