jquery第九期：map，has，each用法
<html><head><script type="text/javascript" src="jquery-1.10.1.js"></script><script type="text/javascript"> $(function() { $("tbody td:nth-child(2)").each(function(n) { $(this).html($(this).prev("td").html()+"."+$(this).html()); } ); });</script></head><body><table width="700" border="1" align="center" id="second"></table><table width="300" border="1" align="center" id="first"> <tr> <td>用户标识</td> <td>用户姓名</td> <td>用户年龄</td> <td>用户密码</td> </tr> <tr id="abc"> <td id="cde">A</td> <td>张三</td> <td>12</td> <td>hehe1</td> </tr><tr> <td>B</td> <td>李四</td> <td>13</td> <td>hehe2</td> </tr><tr> <td>C</td> <td>王五</td> <td>14</td> <td>hehe3</td> </tr><tr> <td>D</td> <td>牛六</td> <td>15</td> <td>hehe4</td> </tr></table></body></html>