使用JavaScript适时的计算用户当前输入的字符数函数代码：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JavaScript统计字符数</title>
<script language="javascript">
function CountWords(obj, show_id){
var fullStr = obj.value;
var charCount = fullStr.length;
var rExp = /[^A-Za-z0-9]/gi;
var spacesStr = fullStr.replace(rExp, ' ');
var cleanedStr = spacesStr + ' ';
do{
var old_str = cleanedStr;
cleanedStr = cleanedStr.replace(' ', ' ');
}while( old_str != cleanedStr );
var splitString = cleanedStr.split(' ');
document.getElementById(show_id).innerHTML=charCount;
}
</script>
</head>
<body>
<form>
<textarea cols="40" rows="5" name="x" onkeyup="CountWords(this,'show')" />
</textarea>
</form>
<div id="show">0</div>
</body>
</html>