选中复选框后如何启用单选按钮？

<input type="checkbox" id="checkbox"> 选中复选框启用单选按钮
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<input type="radio" name="radio" id="radio1" disabled> 单选按钮1
<input type="radio" name="radio" id="radio2" disabled> 单选按钮2

var checkbox = document.getElementById("checkbox");
var radio1 = document.getElementById("radio1");
var radio2 = document.getElementById("radio2");

checkbox.addEventListener("change", function() {
  if (checkbox.checked) {
    radio1.disabled = false;
    radio2.disabled = false;
  } else {
    radio1.disabled = true;
    radio2.disabled = true;
  }
});