1 <form id="form1">
 2         <h2>增加管理员</h2>
 3         <table>
 4             <tr>
 5                 <td>姓名：</td>
 6                 <td>
 7                     <input name="username"/>
 8                     <span>*</span>
 9                 </td>
10                 <td>
11                     <div class="vali_info">
12                      10个字符以内的字母、数字或下划线的组合
13                     </div>
14                 </td>
15             </tr>
16             <tr>
17                 <td>密码：</td>
18                 <td>
19                     <input type="password" name="pwd"/>
20                     <span>*</span>
21                 </td>
22                 <td>
23                     <div class="vali_info">6位数字</div>
24                 </td>
25             </tr>
26             <tr>
27                 <td></td>
28                 <td colspan="2">
29                 <input type="submit" value="保存"/>
30                 <input type="reset" value="重填"/>
31                 </td>
32             </tr>                
33         </table>
34     </form>

 1 table{width:700px}
 2 /*???a????μ?μú1??￡?μún??￡?×?oóò???td×ó?a??*/
 3 td:first-child{width:60px}
 4 /*IE2??§3?nth-child*/
 5 td:nth-child(2){width:200px}
 6 /*IE*/
 7 td:first-child+td{width:200px}
 8 /*IE2??§3?--?éò???×ü?í?èà′μ÷?ú
 9 td:last-child{width:340px}*/
10 td span{color:red}
11 
12 .vali_info{/* ò3??3?ê?￡??é?¤???￠2???ê? */
13     display:none;
14 }
15 .txt_focus{/*μ±??±??ò??μ??1μ?ê±′?é?*/
16     border-top:2px solid black;
17     border-left:2px solid black;
18     background-color: yellow;
19 }/*μ±??±??òê§è￥?1μ?ê±í???*/
20 
21 .vali_success,.vali_fail{
22     background-repeat:no-repeat;
23   background-position:left center;
24     display:block;
25 }
26 /* ?é?¤???￠￡o?é?¤í¨1yê±μ??ùê? */
27 .vali_success{
28     background-image:url("../images/ok.png");
29     padding-left:20px;
30     width:0px;height:20px;//注意这里的需要隐藏文字的样式
31     overflow:hidden;//隐藏文字overflow不可缺少
32 }
33 /* ?é?¤???￠￡o?é?¤ê§°üê±μ??ùê? */
34 .vali_fail{
35     background-image:url("../images/err.png");
36     border:1px solid red;
37     background-color:#ddd;
38     color:red;
39     padding-left:30px;
40 }

 1 //Step1:为name为username和pwd的文本框绑定获得焦点事件
 2 //获得表单对象: 
 3 var form=document.forms[0],
 4     txtName=form.username,
 5     txtPwd=form.pwd;
 6 txtName.onfocus=getFocus;
 7 txtPwd.onfocus=getFocus;
 8 function getFocus(){
 9   //this->当前文本框
10   //当前文本框边框加粗
11   this.className="txt_focus";
12   //清除旁边div的class
13   var div=this.parentNode.nextElementSibling
14            .firstElementChild;
15   div.className="";
16 }
17 txtName.onblur=function(){
18   vali(this,/^\w{1,10}$/);
19 }
20 function vali(txt,reg){
21   //清除当前文本框的class
22   txt.className="";
23   //获取旁边div
24   var div=txt.parentNode.nextElementSibling
25           .firstElementChild;
26   //用reg测试当前文本框的内容
27   //如果通过,就修改div的class为vali_success
28   //增加true，false是为了方便函数后续的判断，需要了解；
29   if(reg.test(txt.value)){
30     div.className="vali_success";
31     return true;
32   }
33   //否则修改div的class为vali_fail
34   else{
35     div.className="vali_fail";
36     return false;
37   }
38 }
39 txtPwd.onblur=function(){
40   vali(this,/^\d{6}$/);
41 }
42 //为表单添加时间监听：注意这里为表单元素，需要注意；
43 form.addEventListener(‘submit‘,function(e){
44                  if(!vali(txtName, /^\w{1,10}$/))
45                         txtName.focus();
46                   else if(!vali(txtPwd,/^\d{6}$/))
47                         txtPwd.focus();
48                     else if(vali(txtName,/^\w{1,10}$/)&& vali(txtPwd,/^\d{6}$/)) {
49                       this.submit();
50                     }
51                      e.preventDefault();
52             })