代码如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>显示输入剩余字数_www.jb200.com</title>
<script>
var maxstrlen=160;
function Q(s){return document.getElementById(s);}
function checkWord(c,textId){
len=maxstrlen;
var str = c.value;
myLen=getStrleng(str);
var wck=Q(textId);
if(myLen>len*2){
c.value=str.substring(0,i+1);
}else{
wck.innerHTML = Math.floor((len*2-myLen)/2);
}
}
function getStrleng(str){
myLen =0;
i=0;
for(;(i<str.length)&&(myLen<=maxstrlen*2);i++){
if(str.charCodeAt(i)>0&&str.charCodeAt(i)<128)
myLen++;
else
myLen+=2;
}
return myLen;
}
</script>
</head>
<body>
<div style="font-size:16px">
控制输入框字符输入，计算输入字符总数,显示剩余字数;<br>
一个英文字符算一个字符，一个中文字符算两个字符计算。
脚本学堂_www.jb200.com，javascript 教程由此开始。
</div>
<div>
<textarea onKeyUp="javascript:checkWord(this,'wordCheck');" onblur="javascript:checkWord(this,'wordCheck');" name="content" style="height:100px;width:200px;overflow-x:hidden;overflow-y:hidden"></textarea>
</div>
<DIV>
还可以输入<span style="font-size: 26px;" id="wordCheck">160</span>个字符 </div>
<textarea onKeyUp="javascript:checkWord(this,'wordCheck1');" onblur="javascript:checkWord(this,'wordCheck1');" name="content" style="height:100px;width:200px;overflow-x:hidden;overflow-y:hidden"></textarea>
</div>
<DIV>
还可以输入<span style="font-size: 26px;" id="wordCheck1">160</span>个字符 </div>
</body>
</html>