Basically, it does matter what backend you have. Most times there is no hard or easy to learn. A person that is good in java would say it is easy to learn, a person that is not so god in java would say that it is hard to learn. Same with time.
When you want to use javascript in the backend end I would recommend the framework koa.
If you don´t want to use javascript as backend, please add the language you want to write it in.