So I have a piece of javascript code in an html document that responds to a button click. I want a new url to open, and if I specify the link in javascript as I've done below, everything works fine.

<input type="submit" id="submitbtn" value="Purchase Module"/>
<script type="text/javascript">
document.getElementById("submitbtn").addEventListener("click",handle_click);
function handle_click() {
var link;
link="http://www.google.com";
window.location.href=link;
}
</script>

Problem is I want to hide the real link on the server side as it includes a username:password. The php script below calls a function (not shown) that generates the link (a string). This also works fine.

<?php
$link=get_page_link();
?>

I want to pass the link string to the javascript and have tried various iterations of link=<?php echo $link ;?> to no avail. As I understand it you can't pass strings this way and you need to use ajax. That's where I'm stuck. Seems like I need a $_POST on the php side and a $_GET on the java side, but not sure on the specifics. Any help would be appreciated. Thanks.