从跨度获得纪元时间

Question

epoch转换器的工作已经完成，但是当我通过id得到span的值并将其复制到broser时给我未定义

<span name ="EpochClock" id="EpochClock"></span>
</div>
<input type="button" onClick="pprint()" value="print" >

    <script language="JavaScript">
      function pprint(){
        // If you want to use element Id
          var a = document.getElementById('EpochClock').value;
          document.write(a);
        // If you want to access by element name
          var b = document.getElementsByName('EpochClock')[0].value;
          document.write(b);
     }
     </script>

任何帮助