问一个none和block的动态控制问题

Question

我想点一下新闻标题就显示新闻内容，再点一次新闻标题，新闻内容就不显示，下面的代码那里写不对呀<table width="200" border="1" id="abcd" style="display:none">
  <tr>
    <td>新闻内容</td>
  </tr>
</table>
<span onclick="javascript:document.getElementById('abcd').style.display=='none'?'block':'none'">新闻标题</span>

Answer 1

表达式用的不对 <span onclick="javascript:document.getElementById('abcd').style.display=document.getElementById('abcd').style.display=='none'?'block':'none'">新闻标题 </span>

Answer 2

改成下面的也不对呀，怎么修改
<span onclick="javascript:document.getElementById('abcd').style.display=document.getElementById('abcd').style.display='none'?'block':'none'">新闻标题 </span>

Answer 3

<span onclick="javascript:document.getElementById('abcd').style.display=document.getElementById('abcd').style.display=='none'?'block':'none'">新闻标题 </span>和你贴出来的是有区别的：<span onclick="javascript:document.getElementById('abcd').style.display=document.getElementById('abcd').style.display='none'?'block':'none'">新闻标题 </span>

Answer 4

<span onclick="document.getElementById('abcd').style.display=document.getElementById('abcd').style.display=='none'?'block':'none'">新闻标题  </span>