In previous articles I have written about how to track elements when they enter or leave the browsers viewport. The reason why you might want to track this is when you are doing a test on an element that is outside the viewport on page initialisation, you don't want to count this as a visitor immediately but only when the element is scrolled into view. If the (changed) element is seen by the visitor, you fire an event, not before. In the past I accomplished this by using … [Read more...] about Notify Enter Viewport the proper way: Intersection Observer.