Update log:
Continuously debugging and uploaded several new versions. Some big bugs have been fixed with Array Brackets. If something didn't work, please try again.
Also, some strange disappearance of closing html tags after using js methods split() and join(), but only when they were on the same line as their opening tags, so for now I write these to a new line, which fixed the problem, but this mystery is yet to be solved.
Good news: ReadPixel, which doesn't work when the page runs locally from a file:// url, is now working when run on itch.io. I am assuming the same is true for CopyRect.