If you’re looking for a gentle introduction to using the Fetch API, a modern replacement for XMLHttpRequest-based Ajax-driven pages, this is the place to start!
Today it’s safe to say that most web apps (including PWAs) make requests for resources on-the-fly, or dynamically. This is often referred to as asynchronous resource loading. This is different from resources that load when the page initially loads. Asynchronous resources are requested on demand in specific circumstances and don’t require a full page load.
As mentioned, in most cases, this type of loading has been done via Ajax, which utilizes a technology called XMLHttpRequest to make asynchronous resource calls. In this tutorial, I’m going to go through how to use the Fetch API (official), which now has excellent browser support and is slowly starting to replace XMLHttpRequest.
