Quote from Defining JavaScript Resources In QML:
Some JavaScript files act more like libraries - they provide a set of helper functions that take input and compute output, but never manipulate QML component instances directly.
What if I want a JS file that both:
I could get the "no data stored on every instance" part by, well, not putting global variables in the JS file. But, for some strange reason, a copy of the "code" part seems to be stored for every instance as well. I don't get why this is but I want to know whether I can circumvent it, and at what cost.
I think that the line you quoted from the documentation is incorrect, or at least very poorly worded; you can still have a JS file with .pragma library
in it and manipulate QML objects that are passed in as arguments to its functions. The sentence was probably referring to the previous section.