Button click callback

Instapage allows running javascript code just after anchor or button click. All you have to do is add this code in the Settings - JavaScript header area of your page. 

<script type="text/javascript">

window.instapageAnchorClick = function( element ){

    // here is your code to execute
    // element variable holds clicked element

};

</script>

Inside the "instapageAnchorClick" function where you have the text 

    // here is your code to execute
    // element variable holds clicked element

You will need to add in your own code, like for example an event tracking code or a Facebook pixel.