cdnjs is a free distributed JS library delivery service.
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
Google Cloud Trace is a distributed tracing system that collects latency data from applications and displays it in the Google Cloud Console.
Google Hosted Libraries is a stable, reliable, high-speed, globally available content distribution network for the most popular, open-source JavaScript libraries.
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.
Underscore.js is a JavaScript library which provides utility functions for common programming tasks. It is comparable to features provided by Prototype.js and the Ruby language, but opts for a functional programming design instead of extending object prototypes.