There are a lot of cool animations on the IFLY KLM Magazine’s ultimate travel collection of 50 most beautiful places in the world minisite. Eric Brewer has recreated the scroll animation in the slider where you can see the number slide up when you scroll and it the background colour of the number is filled with the image that is loaded next.
If you are having trouble with the pen, try the archived copy on GitHub
Number Slider Transition Snippet
See the Pen Knockout Text Transition by Eric Brewer (@ebrewe) on CodePen.0