It's heavily inspired by "You might not need jquery" as the intro shows! Lots of the methods are just like in these examples, only with looping/multiple nodes. Example:
$(el).addClass(className); vs el.classList.add(className);
Do not work the same. jQuery (and Umbrella JS) deal with multiple elements and with multiple class names in multiple formats (as a string, as arguments, etc). That's why I find myself still using Umbrella JS from time to time in smaller non-React projects! Just makes everything a lot easier, for 3kb.