还剩多少字节

<div class="dream_name">
                	<p><strong>我的梦想是：</strong><input class="input_text" id="dreamtitle" name="dreamtitle" type="text" maxlength="40" /></p>
                    <span>(最多可输入<strong id="stat_max"></strong>个字符，当前共<strong  id="stat_total"></strong>个字符，还可输入<strong id="stat_left" ></strong>个字符)</span>
                </div>

 

 <script language="javascript" type="text/javascript">
<!--
var
// 获取元素
$ = function(element) {
 return (typeof(element) == 'object' ? element : document.getElementById(element));
},
// 判断浏览器
brower = function() {
 var ua = navigator.userAgent.toLowerCase();
 var os = new Object();
 os.isFirefox = ua.indexOf ('gecko') != -1;
 os.isOpera = ua.indexOf ('opera') != -1;
 os.isIE = !os.isOpera  &&  ua.indexOf ('msie') != -1;
 os.isIE7 = os.isIE  &&  ua.indexOf ('7.0') != -1;
 return os;
},
// 事件操作(可保留原有事件)
eventListeners = [],
findEventListener = function(node, event, handler){
 var i;
 for (i in eventListeners){
  if (eventListeners[i].node == node  &&  eventListeners[i].event == event  &&  eventListeners[i].handler == handler){
   return i;
  }
 }
 return null;
},
myAddEventListener = function(node, event, handler){
 if (findEventListener(node, event, handler) != null){
  return;
 }
 if (!node.addEventListener){
  node.attachEvent('on' + event, handler);
 }else{
  node.addEventListener(event, handler, false);
 }
 eventListeners.push({node: node, event: event, handler: handler});
},
removeEventListenerIndex = function(index){
 var eventListener = eventListeners[index];
 delete eventListeners[index];
 if (!eventListener.node.removeEventListener){
  eventListener.node.detachEvent('on' + eventListener.event,
  eventListener.handler);
 }else{
  eventListener.node.removeEventListener(eventListener.event,
  eventListener.handler, false);
 }
},
myRemoveEventListener = function(node, event, handler){
 var index = findEventListener(node, event, handler);
 if (index == null) return;
 removeEventListenerIndex(index);
},
cleanupEventListeners = function(){
 var i;
 for (i = eventListeners.length; i > 0; i--){
  if (eventListeners[i] != undefined){
   removeEventListenerIndex(i);
  }
 }
};
-->
</script>
<script language="javascript" type="text/javascript">
<!--
/*
 - statInput 输入限制统计
 - 长度超出_max的话就截取...貌似没有更好的办法了
*/
function statInput(e, _max, _exp) {
 e   = $(e);
 _max  = parseInt(_max);
 _max  = isNaN(_max) ? 0 : _max;
 _exp  = _exp==undefined ? {} : _exp;
 
 if(e==null || _max==0) {
  alert('statInput初始化失败！');
  return;
 }
 
 var
 // 浏览器
 _brower  = brower();
 // 输出对象
 _objMax  = _exp._max==undefined ? null : $(_exp._max),
 _objTotal = _exp._total==undefined ? null : $(_exp._total),
 _objLeft = _exp._left==undefined ? null : $(_exp._left),
 // 弹出提示
 _hint  = _exp._hint==undefined ? null : _exp._hint;
 
 // 初始统计
 if(_objMax!=null) _objMax.innerHTML = _max;
 if(_objTotal!=null) _objTotal.innerHTML = 0;
 if(_objLeft!=null) _objLeft.innerHTML = 0;
 
 // 设置监听事件
 // 输入这个方法比较好.
 // 但是Opera下中文输入跟粘贴不能正确统计...相当BT的东西...
 // 如果不考虑Opera的话就用这个吧.否则就老老实实用计时器.
 if(_brower.isIE) {
  myAddEventListener(e, "propertychange", stat);
 }else{
  myAddEventListener(e, "input", stat);
 }

 
 // 统计函数
 var _len, _olen, _lastRN, _sTop;
 _olen = _len = 0;
 function stat() {
  _len = e.value.length;
  if(_len==_olen) return;  // 防止用计时器监听时做无谓的牺牲...
  if(_len>_max) {
   _sTop = e.scrollTop;
   // 避免IE最后俩字符为'\r\n'.导致崩溃...
   _lastRN = (e.value.substr(_max-1, 2) == "\r\n");
   e.value = e.value.substr(0, (_lastRN ? _max-1 : _max));
   if(_hint==true) alert("你太调皮了，都已经超出字符限制了，为师跟你说过，叫你不要输那么多字~~.");
   // 解决FF老是跑回顶部
   if(_brower.isFirefox) e.scrollTop = e.scrollHeight;
  }
  _olen = _len = e.value.length;
  
  // 显示已输入字数
  if(_objTotal!=null) _objTotal.innerHTML = _len;
  // 显示剩余可输入字数
  if(_objLeft!=null) _objLeft.innerHTML = (_max-_len)<0 ? 0 : (_max-_len);
 }
 
 stat();
}
-->
</script>
<script language="javascript" type="text/javascript">
<!--
myAddEventListener(window, "load", testStatInput);
function testStatInput(){
 statInput('dreamtitle', 40, {_max : 'stat_max', _total : 'stat_total', _left : 'stat_left', _hint : true});
}
-->
</script>