js判断剩余的字数

<SCRIPT LANGUAGE=”JavaScript”>
<!– Begin
maxLen = 130;

function checkMaxInput(form) {
if (form.message.value.length > maxLen)
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”> 你只可以输入130个字<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″>还可以输入font>
</form>