jquery选择器 - 选择每个表行中的第二个span子节点

Question

我有以下标记:

<table>
<thead>
...
</thead>
<tbody>
<tr>
    <td>
      <span class='select_me' id='42'></span>
    </td>
     <td>
      <span class='select_me' id='43'></span>
     </td>
  </tr>
 <tr>
    <td>
      <span class='select_me' id='50'></span>
    </td>
     <td>
      <span class='select_me' id='54'></span>
     </td>
  </tr>
</table>

我如何在每一行中选择第二或第一跨度'select_me'？我觉得它是这样的 - 我想得到身份证

$("td").each(function(){
v = $(this).children(".select_me:first").attr("id");
});

但它输出'undefined',任何帮助将不胜感激

Answer 1

您可以使用:eq选择器:

$("tr").each(function() {
    var firstId = $("span.select_me:eq(0)", this).attr("id");
    var secondId = $("span.select_me:eq(1)", this).attr("id");
});

由于<span>每行只有两个元素,因此您还可以使用:first和:last选择器:

$("tr").each(function() {
    var firstId = $("span.select_me:first", this).attr("id");
    var secondId = $("span.select_me:last", this).attr("id");
});