The HR interview was followed by tech interview. HR informed me that 1st round of tech interview would comprise of JS / HTML / CSS but I was surprised when interviewer in the 1st round started asking me Data Structures & Algorithms questions. Fortunately, I was able to code the problem given by him successfully. He also asked me Java Script and React questions, which I answered (I may have not answered 2/3 questions out of 20-25 questions).
The interview went very well, also had healthy discussions with the interviewer.
I was shocked to receive a rejection mail next morning as the interview went very well. I rang the HR for feedback and the feedback I received was that my DS / Algorithm was weak, which I firmly believe was not the case as I was able to solve the problem in the given time.
Anyway, I do not see any reason why I should not have been forwarded to the next round. These guys needs a serious look into their interviewing process else they will not be able to filter talented people.