js textarea 字数限制

function textCounter(field, countfield, maxlimit) {
            if (field.value.length > maxlimit)
                field.value = field.value.substring(0, maxlimit);
            else
                countfield.value = maxlimit - field.value.length;
        }

<form name=myform action="">
    <textarea name="message" cols="28" rows="5" onKeyDown="textCounter(message,remLen,1000);" onKeyUp="textCounter(message,remLen,1000);"></textarea>
    您还可以输入:<input name="remLen" type="text" value="1000" size="5" readonly="readonly">个字符
</form>