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Facebook Pixel - Is Element Visible
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| // https://developers.facebook.com/docs/facebook-pixel/advanced/ | |
| // This code should be loaded together with Facebook Pixel | |
| 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); | |
| }; |
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