The article related to this video is available on Photics.com — Free Template Tuesday #10 – Tumult Hype “Reveal” – Photics.com
The “Reveal” template is a great way to compare two similar images, as it allows the website visitor to control a slider. One one side of the slider is one image, on the other side of the slider is the other image. This can be great for displaying before-and-after images, such as a construction project or perhaps weight loss. It's a way to show change between the two images.Although, this project doesn't use images. It uses text and emoji. 
Knowledge JavaScript is not required for this template. It's simply based on the inherent features of the Tumult Hype app. By adding a few interactive settings, a Hype project can have this cool interactive feature. The technique of using groups to hide or show elements can also be used as animation.