Ajax revolutionized web development by allowing developers to create interactive client-side applications that communicated with servers only when necessary, skipping the constant refresh cycle of earlier models. While Ajax usually makes applications run smoother, it can also introduce strange performance and resilience issues. In this course, Sasha Vodnik provides you with the details you need to create fast and reliable web applications using Ajax in the background. Sasha dives into the basics of XHR—the fundamental building block of Ajax—as well as the newer Fetch API. Plus, he explains how to write Ajax whether you're using AngularJS, React, or jQuery. Throughout the course, he shares tips for making smart code design decisions.