I had 6 companies interviews in 1.5 months and want to share some experience with the community. As it usually happens I had NDA for most of them so can't share exact questions, but will give some generic things instead.

Some preparations:
LC: Easy 189, Medium 240, Hard 49, ~50 mock interviews
PRMP: for algorithms and f/e mock interviews
YOE >10

Was trying to find any info about f/e system design rounds, but the information is very limited, and in most cases, you have to rely on your own experience.

Hiring platforms

1. Tripplebyte
   Interviewed there to get straight to on-site without extra screening. They allow one practice interview first and then you can have a final interview with them. If that goes well they'll recommend you to other companies for on-site. After I had my practice interview they've decided that I don't need a final one and added me to the recommendations list.

The interview was 2 hours long, mostly front-end. Both coding (e.g. create Kanban board) and theory. Some basic algorithms questions on complexity, networking, performance optimizations. Very friendly interviewer and reasonable questions. Highly recommended.

2. Inter-ing io
   Same idea as tripplebyte, but they have SDE generalist questions. Had 2 or 3 one hour interviews, all algorithms. Nothing front-end specific. Got into the recommendations list, but I only saw 1 or 2 f/e positions available there. Again, very friendly interviewers, a good opportunity to practice anyways.

Companies

1. 🚫 Microsoft
   Initial screening: count islands and follow up to re-count them if new dots are added to the map. Solved fast, and the only concern was that I might've not communicated follow up perfectly. I had plenty of time left, the interviewer seemed to be ok with my answer and asked to move into asking questions. Was expecting to get into the next round, but didn't happen. Have no idea why 🙃

2. 😒 Bloomberg
   Initial screening: Median of arrays, related followups
   Got invited to on-site, but rejected it. Didn't feel like Bloomberg would be a good career path 😐

3. ✅ Zoox
   Went straight to a full virtual interview through tripplebyte.

   • Math & logic - full hour to solve math-related problems, nothing crazy and very exciting. The interviewer gave some hints here and there, but overall it went good.
   • Algo on linked lists and graphs
   • Code some business logic (provided with input data, need to code calculations based on it)
   • Update existing Vue-based app (have no prior experience), basic coding
   • Call with a manager, bits-related question in the end

   This one went well, not perfect for sure but I was happy overall. Got an offer. Very good experience overall.

4. ✅ Another Zoox-like startup
   Went straight to full virtual interview through tripplebyte.

   • F/e UI coding with a framework of choice
   • Debug & bug fixing with some spaghetti code
   • Design a web crawler
   • Behavioral
   • Call w/manager

   I felt like I bombed design round (was my first interview for a while and I didn't get prepared for sys design at all, so first half I was panicking a lot) and was expecting reject, but got an offer.

5. ✅ Facebook
   Initial screening: F/e related questions (I saw some of them on Glassdoor), 1 string algo using stacks (LC medium).
   Virtual Onsite:
   - Design common component (e.g. poll widget, data table, etc)
   - F/e related code questions. Saw some of them on Glassdoor
   - Medium-hard algo on strings
   - Behavioral
   - Design API layer for app

   All went ok except I felt bad about the last round, so was preparing myself for reject. Got an offer.

6. 😯 Square
   Initial screening 1: F/e related, extend existing app. Basic coding.
   Initial screening 2: F/e related, build UI around algo.
   Virtual Onsite:
   - Encode / decode on strings
   - DFS/BFS related question, coded both solutions
   - Design booking system (known in advance). I prepared a diagram before the interview so we had enough time to discuss different use cases. Interviewers asked for a copy of diagram and seemed to be happy with it. That was a very exciting round. Having some time to prepare the design is a golden opportunity to think about various aspects that you'd miss on interview due to time constrains
   - 2 calls with teams PMs
   - Previous experience (full hour talking about past project, digging into details)
   - Behavioral & leadership

   I had very positive feedback from HR after initial screenings, and I think this was my best on-site interview performance out of all. Was quite confident about results. Then in about a week after, HR said that teams I was interviewed with are filled already and I need to wait for a new one. That was super confusing, felt like a soft reject, but with positive feedback. Not sure what was that, but it's extremely weird. I had other offers pending, so declined. Overall experience was great, except the last step 😁

--

I was planning to apply to Google & Netflix, but was exhausted enough to stop. Picked FB in the end.

To my front-end fellows: it is hard to predict the interview, especially the system design round. It's more about applying your experience. It's also hard to advise if lots of LC is required. Half of the interviews were pure f/e without any medium/hard algorithms required. On the other hand, another half needed it a lot. Overall I'd say it's good to have an understanding for all algo groups, and if I'd change anything in preparations then I'd probably haven't tried to solve too much of DP problems.

It looks like companies want you to know LC mid and all f/e topics. No one cares about react or angular, or your favorite grid system