HTML表单如果选择了一个单选条件，则强制输入

<form>
  <label for="condition">选择一个条件：</label>
  <select id="condition" name="condition" required>
    <option value="">请选择</option>
    <option value="option1">选项1</option>
    <option value="option2">选项2</option>
    <option value="option3">选项3</option>
  </select>
  
  <label for="inputField">输入字段：</label>
  <input type="text" id="inputField" name="inputField" required>
  
  <input type="submit" value="提交">
</form>

<script>
  // 使用JavaScript监听选择条件的变化
  var conditionSelect = document.getElementById("condition");
  var inputField = document.getElementById("inputField");
  
  conditionSelect.addEventListener("change", function() {
    if (conditionSelect.value !== "") {
      inputField.setAttribute("required", "required");
    } else {
      inputField.removeAttribute("required");
    }
  });
</script>