类似微博在文本框中控制别人输入字数

<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
maxLen = 130; // max number of characters allowed
function checkMaxInput(form) {
if (form.message.value.length > maxLen) // if too long.... trim it!
form.message.value = form.message.value.substring(0, maxLen);
// otherwise, update 'characters left' counter
else form.remLen.value = maxLen - form.message.value.length;
}
//  End -->
</script>

<form name=myform action="YOUR-SCRIPT.CGI">
<font size="1" face="arial, helvetica, sans-serif"> ( 朝暮数据www.zhaomu.com )<br>
<textarea name=message wrap=physical cols=28 rows=4 onKeyDown="checkMaxInput(this.form)"
onKeyUp="checkMaxInput(this.form)"></textarea>
<br>
<input readonly type=text name=remLen size=3 maxlength=3 value="130"> www.zhaomu.com</font>
</form>