JavaScript 实时统计字数的代码

类似微博的字数统计功能，代码如下：

<script language="javascript">  
function countChar(textareaName,spanName)
{  
  document.getElementById(spanName).innerHTML = 140 - document.getElementById(textareaName).value.length;
}  
</script>  
还可以输入<span id="counter">140</span>字<br/>
<textarea id="status"  name="status" rows="6" cols="40" onkeydown='countChar("status","counter");' 
onkeyup='countChar("status","counter");'></textarea>

另外一种实现方法：

<script>
function title_len(){
 var value = $('#news_title').val().length;
 if(value == 80){
     var string = "<span>"+value+"/80</span>";
 }else{
     var string = "<span>"+value+"</span>/80";
 }
  $('#titlelen').html(string);
}
</script>