代码如下：
<form action="" method=post name=form>
<script language=javascript>
function gbcount(message,total,used,remain)
{
var max;
max=total.value;
if(message.value.length > max){
message.value = message.value.substring(0,max);
used.value = max;
remain.value = 0;
alert('留言不能超过50个字!');
}
else{
used.value = message.value.length;
remain.value = max - used.value;
}
}
</script>
<body>
<textarea name='GuestContent' cols='60' rows='6' οnkeydοwn=gbcount(this.form.GuestContent,this.form.total,this.form.used,this.form.remain); οnkeyup=gbcount(this.form.GuestContent,this.form.total,this.form.used,this.form.remain);></textarea>
<br>
最多字数：<INPUT disabled maxLength=4 name=total size=3 value=50>
已用字数：<INPUT disabled maxLength=4 name=used size=3 value=0>
剩余字数：<INPUT disabled maxLength=4 name=remain size=3 value=50>
</form>
代码如下：
<script language="JavaScript">
<!-- Begin
function textCounter(field, countfield, maxlimit) {
if (field.value.length > maxlimit)
field.value = field.value.substring(0,maxlimit);
else
countfield.value = maxlimit - field.value.length;
}
// End -->
</script>
<form method="POST" action="../0001/success.asp" name=form >
<textarea cols="45" name="memo" rows="8" wrap="on" class="editbox2" onKeyDown="textCounter(this.form.memo,this.form.remLen,160);" onKeyUp="textCounter(this.form.memo,this.form.remLen,160);"></textarea>
<br>
共可输入160字，还剩
<input readonly type=text name=remLen size=3 maxlength=3 value="160" class=editbox1>
字。 <br>
<input type=submit value=" 发送 " class=bottom name="submit">
<input type=reset value=" 重填 " class=bottom name="reset">
</form>