实时显示输入文本框字数

<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("内容不允许超过 1000 个字!");
}
else {
used.value = message.value.length;
remain.value = max - used.value;
}
}
</script>
<form>
<textarea class=cnone name="contents" onmousedown="this.className=‘cdown‘" onmouseover="this.className=‘cup‘" onmouseout="this.className=‘cnone‘" onkeydown=gbcount(this.form.contents,this.form.total,this.form.used,this.form.remain); onkeyup=gbcount(this.form.contents,this.form.total,this.form.used,this.form.remain); cols="80" rows="8" wrap="VIRTUAL" id="contents">
</textarea>
最多字数：<INPUT class=cnone disabled maxLength=4 name=total size=3 value=1000>
已用字数：<INPUT class=cnone disabled maxLength=4 name=used size=3 value=0>
可用字数：<INPUT class=cnone disabled maxLength=4 name=remain size=3 value=1000>
</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("内容不允许超过 1000 个字!");
}
else {
used.value = message.value.length;
remain.value = max - used.value;
}
}
</script>
<form>
<textarea class=cnone name="contents" onmousedown="this.className=‘cdown‘" onmouseover="this.className=‘cup‘" onmouseout="this.className=‘cnone‘" onkeydown=gbcount(this.form.contents,this.form.total,this.form.used,this.form.remain); onkeyup=gbcount(this.form.contents,this.form.total,this.form.used,this.form.remain); cols="80" rows="8" wrap="VIRTUAL" id="contents">
</textarea>
最多字数：<INPUT class=cnone disabled maxLength=4 name=total size=3 value=1000>
已用字数：<INPUT class=cnone disabled maxLength=4 name=used size=3 value=0>
可用字数：<INPUT class=cnone disabled maxLength=4 name=remain size=3 value=1000>
</form>