Comment by schneidmaster

AJAX (Asynchronous Javascript and XML) is purely orthogonal to DOM updates. An AJAX request is just a network request initiated asynchronously via some Javascript on the page, as opposed to a request initiated synchronously when a user clicks a link or submits a form. Response data from an AJAX request could be used to make a direct DOM mutation, update React state, log to the console, or anything else the developer wants.