In my experience job descriptions in IT/development are pretty much meaningless, very few roles condense easily into a few lines and there will always be ancillary tasks that fall outside of it.
However these additional responsibilities you describe sound, for the most part, like a reasonably common career development trajectory for a junior developer. And if they are taking up a non-trivial amount of your time - and most importantly if you are doing them well then they are a good basis to ask for a salary increase.
The best way to do this is to arrange a 1-1 meeting with your manager (or use your next performance review if it's soon enough for you) and make your case about how these additional tasks you are carrying out are bringing value to the company over and above your standard duties. Go armed with specific examples of ones that went well and of skills you have acquired.
Attitude is key here, going in with
I'm doing all this stuff that isn't in my job description, it's not fair. You need to pay me more
isn't likely to go down well. Whereas:
I really feel like I've grown during my time here. I've learnt language x and used it to implement front end widgets a, b & c and I really feel that I'm bringing much more value to the company as a result
is much more positive and get's your manager thinking along the right lines i.e. about what they are getting for their money.