Agora Test / VisibilityTrigger_content_trigger

<!-- Facebook Pixel Code -->
<script>
!function(f,b,e,v,n,t,s){if(f.fbq)return;n=f.fbq=function(){n.callMethod?
n.callMethod.apply(n,arguments):n.queue.push(arguments)};if(!f._fbq)f._fbq=n;
n.push=n;n.loaded=!0;n.version='2.0';n.queue=[];t=b.createElement(e);t.async=!0;
t.src=v;s=b.getElementsByTagName(e)[0];s.parentNode.insertBefore(t,s)}(window,
document,'script','//connect.facebook.net/en_US/fbevents.js');

fbq('init', '123456');
fbq('track', 'PageView');


var executeWhenElementIsVisible = function(dom_element, callback) {

if (!(dom_element instanceof HTMLElement)) {
    console.error('dom_element must be a valid HTMLElement');
}

if (typeof callback !== 'function') {
    console.error(
        'Second parameter must be a function, got',
        typeof callback,
        'instead',
    );
}

function isOnViewport(elem) {
    var rect = elem.getBoundingClientRect();
    var docElem = document.documentElement;
    return (
      rect.top >= 0 &&
      rect.left >= 0 &&
      rect.bottom <= (window.innerHeight || docElem.clientHeight) &&
      rect.right <= (window.innerWidth || docElem.clientWidth)
    );
}

var executeCallback = (function() {
var wasExecuted = false;
return function() {
  if (!wasExecuted && isOnViewport(dom_element)) {
    wasExecuted = true;
    callback();
  }
};
})();

window.addEventListener('scroll', executeCallback, false);
};

var trigger_element_id = document.getElementById('content_trigger');
executeWhenElementIsVisible(trigger_element_id, function() { fbq('trackCustom', 'content_trigger', {custom_param: 'content_trigger'});  });
</script>
<noscript><img height='1' width='1' style='display:none' src='https://www.facebook.com/tr?id=123456&ev=PageView&noscript=1' /></noscript>
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