Changing role. From backend to frontend

Hi everyone, I am working as a ruby on rails backend engineer in a service based giant of India for past 3 years .. Thinking of changing my role to a front-end developer (I know front-end as ruby on rails requires a good amount of front-end knowledge) What are some things to keep in mind while changing roles, also for a 3 year experience, what salary should I expect in Bangalore/Gurgaon...? Also, if you're a front-end developer, what tech do you most predominantly use in day to day coding & also please share your salaries...Thanks !