What kind of questions are asked for the Amazon front end engineer interview. is it more leetcode type questions or more like building widgets with html css javascript
PURE JS
They still ask backend algo questions also.
Like trees and graphs?
Depends on your interviewer. FEE is part of the SDE family. So any technically any question you can ask a SDE - you can ask an FEE.
What kind of js questions? Any platform to practice them similar to leetcode for backend?
implement pub sub
It will be mainly focused on front end related stuff but you will have one or two LC based rounds.