Thusly, jQuery is not a Rails dependency anymore. The gem, rails-ujs, was created by developer Dangyi Liu as part of the Google Summer of Code event.
For years, jQuery has been a staple of the Web, handling such tasks as HTML, document traversal and manipulation, and event handling. It's used by 96.4 percent of websites whose library is known, according to W3techs, which surveys usage of Web technologies.
Rails, meanwhile, has been seen as having lost some steam itself in favor of technologies such as Node.js. and Angular.js. The current release is Rails 220.127.116.11.