...E.g. when an element enters the viewport, fade it in. You can add custom offsets per element, or set offsets on the viewport (e.g. always trigger after the element reaches 20% of the viewport) When using the callbacks ScrollTrigger becomes really powerful. You can run custom code when an element enters/becomes visible, and even return Promises to halt the trigger if the callback fails. This makes lazy loading images very easy. The easiest way to start is to create a new instance and add some triggers to it, with all default values. ...