I have been interviewing a lot of folks in recent years, and I should tell you that the listed interview questions are not really frontend technology specific. These are for software engineers who are going to work in some cool products which serves customers at scale.
So, here are my favourite picks in no specific order with which I measure a candidate and also face a quite lot of time in my interviews.
Explain me event loop with a tiniest example.
Stock buy and sell problem : geeksforgeeks.org/stock-buy-sell
Find duplicates in a string, optimise if you are traversing linearly.
Sorting domain names : stackoverflow.com/questions/342590/sorting-..
Numeric keypad problem : geeksforgeeks.org/mobile-numeric-keypad-pro..
Coin change problem based on dynamic programming : geeksforgeeks.org/coin-change-dp-7
Write tests of the previous question.
Design a schema for an order page in an e-commerce site.
Let's discuss about optimising a server rendered react application.
See you there.