Ajax can be used to create single-page apps, in which the entire web app consists of a single document, which uses Ajax to update its content as needed.
Initially Ajax was implemented using the
XMLHttpRequest interface, but the
fetch() API is more suitable for modern web applications: it is more powerful, more flexible, and integrates better with fundamental web app technologies such as service workers. Modern web frameworks also provide abstractions for Ajax.
This technique is so common in modern web development that the specific term "Ajax" is rarely used.