JavaScript实现checkbox全选，当只有一个时不起作用的情况也已经解决

<script language="JavaScript">   function check(field) {    var t = document.noticeForm.selectAll;    if(!document.noticeForm.notice.length){          if(t.checked){              document.noticeForm.notice.checked=true;          }          else{              document.noticeForm.notice.checked=false;            }          }    if (t.checked) {     for (i = 0; i <field.length; i++) {      field[i].checked = true;     }    }    else {     for (i = 0; i <field.length; i++) {      field[i].checked = false;      }    }   }   function isSelect(confirmString){    field = document.noticeForm.notice;    var count = 0;    if(!document.noticeForm.notice.length){           if(document.noticeForm.notice.checked){               count++;           }          }    for (i = 0; i <field.length; i++) {     if(field[i].checked == true){      ++count;     }    }    alert(count);    if(count>0){     return confirm(confirmString);    }     else {     alert请至少选一个！');     return false;    }   }</script><form action="${action}" name="noticeForm" onsubmit="return isSelect('${confirmString}');">    <table border="1" width="95%" bordercolor=#8AB78A>    <tr>       <td align="center"><input type="checkbox" name="" onClick="check(this.form.notice)"/></td>       <td align="center"><strong>状态</strong></td>       <td align="center"><strong>标题</strong></td>       <td align="center"><strong>作者</strong></td>       <td align="center"><strong>发给谁？</strong></td>       <td align="center"><strong>人气/回复</strong></td>       <td align="center"><strong>发布时间</strong></td>       <td align="center"><strong>最后修改</strong></td>       <td align="center"><strong>审核</strong></td>         </tr>     <c:forEach var="notice" items="${pageForm.list}" begin="${(pageForm.currentPage-1)*(pageForm.pageSize)}" end="${(pageForm.currentPage-1)*(pageForm.pageSize)+pageForm.pageSize-1}">    <tr align="center">       <td><input type="checkbox" name="notice" value="${notice.id}"/></td>       <td><c:out value="${notice.statusString}"></c:out></td>       <td>        <a href="servlet/NoticeDetail?id=${notice.id}" title="${notice.title}">        <c:out value="${notice.title}"></c:out>        </a>        <fmt:formatDate var="writeTime" value='${notice.writeTime}' type='both' pattern="yyyy-MM-dd"/>        <jsp:useBean id="now" class="java.util.Date" />      <fmt:formatDate var="today" value="${now}" type="both" pattern="yyyy-MM-dd" />         <c:if test="${writeTime==today}">         <img alt="新公告" src="images/new.gif">        </c:if>       </td>       <td><c:out value="${notice.authorId}"></c:out></td>       <c:set var="author" value="${notice.authorId}"></c:set>       <td><c:out value="${notice.typeString}"></c:out>       <c:out value="(${notice.recipients})"></c:out></td>       <td><c:out value="${notice.readCount}"></c:out>/<c:out value="${notice.replyCount}"></c:out></td>       <td>       <fmt:formatDate value='${notice.writeTime}' type='both' pattern="yyyy-MM-dd HH:mm:ss"/>       </td>       <td>        <fmt:formatDate value='${notice.lastModified}' type='both' pattern="yyyy-MM-dd HH:mm:ss"/>       </td>       <td>        <c:out value="${notice.isAuditString}"></c:out>       </td></tr>              </c:forEach>    </table>    <input type="checkbox" name="selectAll" value="全选" onClick="check(this.form.notice)">全选      <input type="image" src="images/delete.gif" style="cursor: hand;" alt="删除" >删除选定内容