I haven’t tried JS in 8.1 but would be surprised if it has suddenly been disabled altogether (with the correct settings option).
Can you share your “best” attempt at the relevant JavaScript? I’m afraid the one you shared in your last post doesn’t actually do any refreshing, so I strongly suspect the issue is with the code. Checking your browser’s dev tools may offer some clues (e.g. JS errors). Have in mind that you shouldn’t include any <html>, <head>, and <body> tags - those already exist in the webpage. Only the stuff inside <body> is what you should provide.
I can try to share a working example when I’m back in front of my computer, but it’ll be a few days (am currently on holiday)