I'm probably the wrong one for this SRS but I'm viewing that now as differences between describing a program, e.g pseudocode and differences in, shall I say, ways of programming.
I'm a rank amatuer who started to find some sense with Turbo Pascal and the ideas of structured programming. The bulk of my learning was on my own and probably the biggest thing I learned from any course was the idea of breaking things down into smaller chunks using something called "Jacksons Structural Programming" (JSP but to confuse the issue, not to be confused with JSP as in Java Sever Pages).
With that, one drew boxes to show input and output and the program. The basic idea was sort of along the lines that one may not know how to build a house but foundations, walls, roof, etc. could be identified as tasks and "sub tasks" could then be developed, e.g. build a wall could be expanded to lay bricks, mix cement, etc.
From that, within my little bit of formal training, one would go into peseudocode before coding into a language. The idea being that pseudocode can be translated into any number of languages - the steps on how to do are there - all that's needed is a translation into a programing language. In reality, it's not as simple as that but it's not a bad outlook.
With luck, one of the many experienced programmers will chip in with more. Believe me, there are a few forum contributers round here who could lose me with one or two sentances - it's the same in many places on the Internet.
Anyway, that's it for now. I don't think much of that is relavant to wanting to modify some JavaScript but with pseudocode or whatever, ideas can be built on...