Hej!
<script type="text/javascript">
function addMonths(sel){
var elms = document.forms["nyheter"].elements;
var dateSpan = document.getElementById("dateSpan");
var beginDate = elms["inskrivningsdatum"].value;
var monthsToAdd = sel.options[sel.selectedIndex].text;
beginDate = new Date(/^\d+/.exec(beginDate), parseInt(/-(\d+)-/.exec(beginDate)[1], 10) - 1, /\d+$/.exec(beginDate));
var endDate = new Date(beginDate.getFullYear(), beginDate.getMonth() + 1 * monthsToAdd, beginDate.getDate());
elms["inskrivningsdatum2"].value = endDate.getFullYear() + "-" + pad(endDate.getMonth() + 1) + "-" + pad(endDate.getDate());
dateSpan.innerHTML = elms["inskrivningsdatum2"].value;
}
function pad(n){
if (n < 10) return "0" + n;
return n;
}
</script>
<body>
<FORM NAME="nyheter">
<INPUT NAME="inskrivningsdatum" TYPE="hidden" value="2009-07-04">
Inskrivet: 2009-07-04 + antal månader
<select name="months" onchange="addMonths(this)">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
<option selected>6</option>
<option>7</option>
<option>8</option>
<option>9</option>
<option>10</option>
<option>11</option>
<option>12</option>
</select>
Här visas slutdatum med javaskriptets hjälp: <span id="dateSpan"></span><BR>
<INPUT NAME="inskrivningsdatum2" TYPE="hidden" value="Här fixar javascriptet in slutdatum i formen yyyy-mm-dd" >
<BR>
Rubrik:
<BR>
<input name="rubrik" type="text">
<BR>
Meddelande: <BR>
<textarea name="meddelande" cols="40" rows="6"></textarea>
<BR>
<INPUT VALUE="Skicka in" TYPE="button">
</form>
<script type="text/javascript">addMonths(document.forms["nyheter"].elements["months"]);</script>
</body>
