I have a JavaScript which processes the contents/selection of a dropdown box,
loading the associated URL or page.

This works fine.

However what I want is for the URL/Page to load in the main window/frame
(not a new window but one already on screen) and not the current, contents

I have tried using target in various ways with no success.

Pardon any 'dullness', it's my first ever venture into JavaScript

Example of Script is.
/* comments in JavaScript here */
function change_site()
if (confirm('Are you sure you want to change site? ' + site))
{if (site==1) {
window.location.href=document.myform.mypopup.options[site].text; }
else {
window.location.href=document.myform.mypopup.options[site].value;} }