jQuery is the more common of the two in our index: it runs on 26,907 websites against 17 for Locomotive Scroll, and 15 sites use both. Counts come from real scans, not vendor claims.
jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.
Locomotive Scroll is an opinionated JavaScript library that provides smooth scrolling animations and advanced scroll interactions for web applications.
15 sites run both jQuery and Locomotive Scroll. That is 88% of the sites using Locomotive Scroll, the smaller of the two.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.