Developing Facebook’s New Photo Viewer

What this post added

This post details the redesign of Facebook's Photo Viewer, addressing issues of reliability, user experience in News Feed, and cumbersome comment interaction. The engineering effort focused on a CSS-driven lightbox overlay to improve photo loading speed, increase photo viewing engagement, and simplify interaction with captions and comments. Key technical decisions included leveraging CSS for layout to minimize JavaScript, optimizing AJAX calls by separating image and data fetches, and prefetching images to ensure near-instantaneous display.