如果变量为true，如何强制下拉选择？

<select id="mySelect">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

<input type="checkbox" id="forceSelect" />
<label for="forceSelect">强制下拉选择</label>

var selectElement = document.getElementById("mySelect");
var forceSelectCheckbox = document.getElementById("forceSelect");

forceSelectCheckbox.addEventListener("change", function() {
  if (forceSelectCheckbox.checked) {
    selectElement.disabled = true; // 禁用下拉选择框
  } else {
    selectElement.disabled = false; // 启用下拉选择框
  }
});