Checka och Ochecka checkboxar

Jag vill att nar folk klickar i en checkbox for "Delete" i ett formular fraga dom om dom ar sakra pa sitt val.
Forst testar jag en confirm() och on det ar 'true' sa vill jag "checka" den box dom valde.
Om inte, "avchecka" den checkbox dom tryckte pa.

Hur avcheck'ar man en checkbox box?

Kod:

<script language="JavaScript">
<!--
function Delmsg(productID,product_description,fieldname) {
	var msg;
	msg = "---------------------------------------- Caution message --------------------------------------------\n\n\n";
	msg += "Are you sure you want to delete this one?\n\nproductID:\t\t ";
	msg += productID;
	msg += "\nproduct_description:\t";
	msg += product_description;
	msg += "\n\n\n---------------------------------------- Caution message -------------------------------------------\n";
	
	if (confirm(msg)) {
		document.change_product.fieldname.checked;
	} else {
		!document.change_product.fieldname.checked;
	}
	//alert(msg);
}
-->
</script>

Kallelse:

<input type=checkbox name=delete_0 value="500NO" onClick="javascript:Delmsg('500NO','Single Computer, 500K','delete_0')">

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peterbe.com

Hittade det!

<script>
var box;
	box = eval("document.change_product."+fieldname);
	
	if (box.checked != true) {
		box.checked = false;
	} else {
		if (!confirm(msg)) {
			box.checked = false;
		}
	}</script>

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peterbe.com