I have written (and maintained) thousands of AJAX (async, dynamic JS ) operations (Angular, React, Ruby on Rails, ...). It is very easy with raw Selenium WebDriver in Ruby.

Selenium Explicits Waits works. However, using Ruby's block is neater (fast, easy, flexible).

Checkout this article: "Test AJAX Properly and Efficiently with Selenium WebDriver, and Avoid ‘Automated Waiting’"

https://medium.com/swlh/test-ajax-properly-and-efficiently-with-selenium-webdriver-and-avoid-automated-waiting-da3ad878559c