Adds an event handler that runs when an element is displayed in the viewable part of the current window.
An element enters the viewport when the page is scrolled to show any
part of the element. An element also enters the viewport if it was
hidden
or collapsed
and is then shown or expanded in the viewable part of the current window. onViewportEnter()
is not fired for hidden
or collapsed
elements even if they are scrolled into view.
You can also define an event handler using the Properties and Events panel.
handler(event: Event): void The name of the function or the function expression to run when the element enters the viewport.