Gramener Visualization Developer interview questions

Interview process taken 3 to 4 days. First round Skype call with Raghu nandh: (Data Scientist, Gramener). This conversation mostly revolved around me trying to understand from him what the role is about and a little bit on my current role on running projects. It was very positive. I was then set up for a Skype video interview. This was a 15 minutes interview which involved a detailed conversation which started with my introduction, recent projects, python fundamental knowledge.The conversation was totally positive and i was waiting for reply but next when i didnt get any call, i asked HR about my feedback. She said like as i don't have enough knowledge on bootstrap and java script they rejected me.This reeks of no planning on their part and wrongness in wasting my time.

technical questions followed by two rounds of interviews. They asked on html,css and other basic and essential web based question. few aptitude questions followed by 5 programming questions. Can attempt in comfortable language. Python adds an advantage here. In technical interview the started with datastructures. like,"what is data structure?". Then "what kind of data structures are used in database to store tables?" then algorithms followed by OS,DB queries. In the second round the tested the analytical skills.