Data Structures Reference
I recently got double slammed with 2 graph questions during an interview after having navigated for years without getting a graph question. It's wholly irrelevant to my day-to-day work but I do hobby game development sometimes which involves more needs for graphing. Still, I can't do much of anything with a graph on a whiteboard.
Puzzled as to why it's so important to some companies to grill on this stuff, expecting it to be top-of-mind, even for front end roles.