Building an online engineering app?

Question

Electronic commerce

Hello dear,
please help with advice:
I want to make myself an engineering application that would do a bunch of analytics for several input parameters and issue a ready-made section of project documentation (for myself), while I want to:
- then make it online, for access from any device
- maybe later turn it into a service and monetize
it - I'm worried that my code will not be stolen)
- I want this project to help develop in programming in the direction most in demand in terms of vacancies - i.e. I understand that one language is rarely enough, but I want to make this project with just one language in order to study it as much as possible, and then add other languages
at the moment I know a little php, js and c # - in all these languages ​​​​I have already written the working parts of this large program, but I just can’t decide in which language to do it completely,
I honestly like js more, because there, taking into account the possibility of using css, except for the program itself, a lot of room for imagination in terms of interface, design, in c # it’s easier to assemble all this in visual studio, and the logic there seems clearer to me, simpler than js, but there is some kind of boring look, although I probably don’t know everything .. Please give me some advice on which option is better to choose ,
the complexity doesn’t stop me, I’ll study what I don’t know, I just can’t decide in which direction to immerse myself in solving the problem as much as possible

Answer 1

The beginning is adequate, the end is nonsense.
Do you want to start a business or study programming?
Let me explain - these are different tasks, and in order to succeed, they must be separated.