如果flask/html/python中未选中复选框，则禁用提交按钮

Question

我正在用python、html和flask制作一个测验排序函数。我需要确保在让用户单击提交功能之前，选择了带有单选按钮的答案。你知道吗

这是函数的python代码和按钮的html：

     def EnableSubmit():

        sbmt = document.getElementById('submit-button')
        if val.checked == True:
           sbmt.disabled = False
        else:
           sbmt.disabled = True

HTML格式：

<div>
       {% for elem in song_options %}
            <input type="radio" name="song" value = "{{elem}}"> {{elem}} <br>
       {% endfor %}
</div>
<br>
<div>

  <input type="submit" value="Submit" id="submit-button" onClick="EnableSubmit(this)">
  <input type = "hidden" name = "songandartist" value = "{{song_name , song_artist}}">