Suggested change... offset

[tdsmoore]

I've seen some really odd results using the offset option. Perhaps I've missed something or the documentation needs updating to make its use clear?

My understanding is that a positive offset should reduce the viewport dimensions top and bottom by the value e.g. :in-viewport(100) would make the viewport shorter by 200 pixels. Conversely, a negative would increase the viewport height allowing detection of objects before they appear on-screen.

The current release works for me if the element starts outside of this new viewport but if I refresh the page and the element is inside the viewport, then :in-viewport(100) returns false until I scroll to a position where the element starts to leave the viewport.

I think that there are 2 issues, first this code - I think it should be removed;

if (settings.tolerance < 0) { settings.tolerance = $viewportHeight + settings.tolerance; // viewport height - tol }

Secondly, this line;

isVisibleFlag = settings.tolerance ? top <= settings.tolerance && bottom >= settings.tolerance : bottom > 0 && top <= $viewportHeight;

I suggest it's changed to;

isVisibleFlag = settings.tolerance ? (bottom >= settings.tolerance && top <= $viewportHeight - settings.tolerance) : bottom > 0 && top <= $viewportHeight;

I now get the results I had expected.