使单选按钮成为表单中的必填字段

<form>
  <input type="radio" name="gender" value="male" required> Male
  <input type="radio" name="gender" value="female" required> Female
  <input type="submit" value="Submit">
</form>

<form id="myForm">
  <input type="radio" name="gender" value="male"> Male
  <input type="radio" name="gender" value="female"> Female
  <input type="submit" value="Submit">
</form>

<script>
  document.getElementById("myForm").addEventListener("submit", function(event) {
    var gender = document.querySelector('input[name="gender"]:checked');
    if (!gender) {
      alert("Please select a gender");
      event.preventDefault();
    }
  });
</script>