Call a php function from java onclick

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I am using John Resig - Easy Retweet Button h t t p://ejohn.org/blog/retweet/ it is written in java.
It works great but I need to add an action of some type that allows me to log that a user clicked the button.
I under stand that java onclick is just a client side action and what I need is a server side action.
Is there a java to php function app/code in side of Zen Cart already that could be used?
If so can you point it out.

Here is the code I am using for testing. Of course I want the inform function to be a php function.

<script>
function inform(){
alert("You have activated me by clicking the button!")
}
</script>
<?php
echo '<a onclick="inform()" class="retweet" href="http://domain.com/index.php?main_page=contest" target="_blank"> Holiday Contest RT & Follow</a>';
?>

Any suggestions on another way to accomplish the same results welcome.

Thanks in advance

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