Hello,
I want to have the result of the expression ('plus') shown in the pop up (and
in the textbox) when clicking on calculate

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-Strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<link href="style.css" rel="stylesheet" type="text/css" />
<title>Prijsgenerator</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
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function newImage(arg) {
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var preloadFlag = false;
function preloadImages() {
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nieuws_over = newImage("images/nieuws-over.jpg");
affiche_over = newImage("images/affiche-over.jpg");
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// -->
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</head>
<body id="slicebody" onload="preloadImages();">
<table id="Table_01" width="668" border="0" cellpadding="0" cellspacing="0">
<tr>
<td rowspan="2">
<img id="index_01" src="images/index_01.jpg" width="87" height="111" alt=""
/></td>
<td rowspan="2">
<a href="index.html">
<img id="home" src="images/home.jpg" width="237" height="111" alt=""
/></a></td>
<td>
<a href="tickets.html"
onmouseover="window.status='tickets'; changeImages('nieuws',
'images/nieuws-over.jpg'); return true;"
onmouseout="window.status=''; changeImages('nieuws', 'images/nieuws.jpg');
return true;"
onmousedown="changeImages('nieuws', 'images/nieuws-over.jpg'); return
true;"
onmouseup="changeImages('nieuws', 'images/nieuws-over.jpg'); return true;">
<img id="nieuws" src="images/nieuws.jpg" width="59" height="72"
alt="tickets" /></a></td>
<td>
<a href="affiche.html"
onmouseover="window.status='affiche'; changeImages('affiche',
'images/affiche-over.jpg'); return true;"
onmouseout="window.status=''; changeImages('affiche',
'images/affiche.jpg'); return true;"
onmousedown="changeImages('affiche', 'images/affiche-over.jpg'); return
true;"
onmouseup="changeImages('affiche', 'images/affiche-over.jpg'); return
true;">
<img id="affiche" src="images/affiche.jpg" width="55" height="72"
alt="affiche" /></a></td>
<td>
<a href="geschiedenis.html"
onmouseover="window.status='geschiedenis'; changeImages('geschiedenis',
'images/geschiedenis-over.jpg'); return true;"
onmouseout="window.status=''; changeImages('geschiedenis',
'images/geschiedenis.jpg'); return true;"
onmousedown="changeImages('geschiedenis', 'images/geschiedenis-over.jpg');
return true;"
onmouseup="changeImages('geschiedenis', 'images/geschiedenis-over.jpg');
return true;">
<img id="geschiedenis" src="images/geschiedenis.jpg" width="54"
height="72" alt="geschiedenis" /></a></td>
<td>
<a href="contact.html"
onmouseover="window.status='contact'; changeImages('contact',
'images/contact-over.jpg'); return true;"
onmouseout="window.status=''; changeImages('contact',
'images/contact.jpg'); return true;"
onmousedown="changeImages('contact', 'images/contact-over.jpg'); return
true;"
onmouseup="changeImages('contact', 'images/contact-over.jpg'); return
true;">
<img id="contact" src="images/contact.jpg" width="57" height="72"
alt="contact" /></a></td>
<td rowspan="2">
<img id="index_07" src="images/index_07.jpg" width="119" height="111"
alt="" /></td>
</tr>
<tr>
<td colspan="4">
<img id="index_08" src="images/index_08.jpg" width="225" height="39" alt=""
/></td>
</tr>
</table>
<div id="wrap">
<div id="container">

<div id="left_kollom">

<div id="menu"> <br/>
<a href="index.html" >HOME<span class="wit">Ga naar de
homepage</span></a>
<a href="tickets.html" >NIEUWS &amp; TICKETS<span class="wit">
</span></a>
<a href="volgendjaar.html" >TW 2007<span class="wit">Rock Werchter
2007</span></a>
<a href="veiligheid.html" >VEILIGHEID<span class="wit">Veiligheid in
Werchter</span></a>
<a href="kamperen.html" >KAMPEREN<span class="wit">Kamperen in
Werchter</span></a>
<a href="generator.html" >PRIJSGNRTR<span class="wit">Beperk uw
budget</span></a>
<a href="http://www.laurenspieters.be" >PORTFOLIO<span
class="wit">Bezoek mijn portfolio</span></a>
<a href="about.html" >ABOUT<span class="wit">Meer over de
site</span></a>
<a href="contact.html" >CONTACT<span class="wit">Contacteer
mij</span></a>
</div>
<br /> Enkele links: <br/>
<a href="http://www.rockwerchter.be/">Offici&euml;le site</a><br />
<a href="http://www.proximusgoformusic.be/">Ticket service</a><br />
<a href="http://www.standaard.be/festivals /">Andere festivals</a><br />
<a href="http://www.nmbs.be/">Trein</a>

</div>

<div id="right_kollom">
<div class="main_artikel"> <br/>
<h3> CONTACT </h3>
<div>

<script type="text/javascript">
<!--
function plus(form1){
form1.getal6.value=parseFloat(form1.getal1.value) +
parseFloat(form1.getal2.value) + parseFloat(form1.getal3.value)
+ parseFloat(form1.getal4.value) + parseFloat(form1.getal5.value);
}

function popup(form1){
window.alert("Uw totale uitgaven bedragen " + plus )
}

//-->
</script>

<h2 class="style1">Bereken uw uitgaven</h2>
<br/>
<span class="style1">Geef uw uitgaven in in elke vakje en klik op berekenen
voor het totaalbedrag te zien en op reset om opnieuw te beginnen.</span>
<form action="">
<table>
<tr><td><span class="style2">Ticket : </span></td>
<td><input type="text" size=5 name="getal1"/></td></tr>
<tr><td><span class="style2">Kamping : </span></td>
<td><input type="text" size=5 name="getal2"/></td></tr>
<tr><td><span class="style2">Vervoer : </span></td>
<td><input type="text" size=5 name="getal3"/></td></tr>
<tr><td><span class="style2">Eten : </span></td>
<td><input type="text" size=5 name="getal4"/></td></tr>
<tr><td><span class="style2">Drank : </span></td>
<td><input type="text" size=5 name="getal5"/></td></tr>
<tr><td colspan=2><hr/></td>
<td></td></tr>
<tr><td><span class="style2">Resultaat : &euro;</span></td>
<td><input type="text" size=5 name="getal6" onfocus="blur()"/><br/></td></tr>
</table>
<table>
<tr><td><input type="button" value="CALCULATE" onclick="plus(this.form)"/></td>
<td><input type="reset" value="RESET" onclick="reset"/></td></tr>
</table>
</form>
</div>
</div>