从类名中获取数字

Question

我有动态生成的 div 部分，类名以数字结尾。我想从类属性中获取数字我想从类 submit-1 (1),submission-2 (2) 中获取数字，并像在代码段中一样尝试。我发现了错误未定义的匹配函数。如何从类属性中获取数字$(document).ready(function(){  var num = $('.submission-').attr('class').match(/\d+$/)[0];  console.log(num);});<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script><div class="webform submission-1">   <span class="first">1</span>   <span class="second">11</span> </div><div class="webform submission-2">   <span class="first">2</span>    <span class="second">22</span> </div><div class="webform submission-3">   <span class="first">3</span>    <span class="second">33</span>  </div><div class="webform submission-4">   <span class="first">4</span>    <span class="second">44</span>  </div><div class="webform submission-12">   <span class="first">12</span>     <span class="second">1212</span>  </div>