js 判断文本框输入字段做限制输入

 

 

 1 <tr>    
 2                     <th>审核原因:</th>
 3                     <td align="left" >
 4                     <textarea id="subject" name="note" class="normal" onkeyup="checkLength(this)" maxlength="255" accesskey="1" tabindex="11"></textarea>
 5                     <br/>
 6                     <span id="subjectchk">还可输入
 7                     <strong id="checklen" style="color: #FF0000">255</strong>
 8                           个字符
 9                     </span>
10                     <span id="postNameRule" class="spn_flag_1" style="display: none"></span>
11                     </td>
12                 </tr>

 

 

 1 <script type="text/javascript">   
 2      //光标离开这个textField就验证该文本框是否为空
 3      function check(){          
 4          var forumPost = document.getElementById("subject");
 5          var forumPostName = forumPost.value;
 6          var subjectchkRule = document.getElementById("subjectchk");
 7          var postNameRule = document.getElementById("postNameRule");
 8           
 9          postNameRule.style.color="#FF0000";
10          if(forumPostName == ""){
11              subjectchkRule.style.display="none";
12              postNameRule.style.display="none";
13              postNameRule.innerHTML="*原因不能为空";
14              forumPost.focus();                  
15          }
16          else{
17              postNameRule.innerHTML="";
18          }           
19           
20      }
21       
22      // 只要键盘一抬起就验证编辑框中的文字长度，最大字符长度可以根据需要设定
23      function checkLength(obj)  { 
24           
25          var maxChars = 255;//最多字符数     
26          var curr = maxChars - obj.value.length; 
27          if( curr > 0 ){
28              document.getElementById("checklen").innerHTML = curr.toString(); 
29          }else{
30              document.getElementById("checklen").innerHTML = '0';
31              document.getElementById("subject").readOnly=true;
32          }
33      } 
34 </script>

 

posted @ 2016-07-21 14:45  _DongGe  阅读(479)  评论(0)    收藏  举报