OK. It took me several tries, but I got the MicroB settings right to stop the Java Script requests. There are several other threads about this but none of them were clear enough for me to do right the first 50 or so tries. Here it is step by step for what worked:

1. Open the MicroB web browser
2. type about:config into the address bar amd hit return
3. In the first box labeled Name type or paste the following:

capability.principal.codebase.p0.granted

4. In the box labeled Value type or paste the following:

UniversalXPConnect UniversalBrowserRead

5. click the Set Preference button
6. after the page refreshes, delete anything in either the Name or Value boxes
7. In the first box labeled Name type or paste the following:

capability.principal.codebase.p0.id

8. In the box labeled Value type or paste the following:

file://

9. click the Set Preference button
10. after the page refreshes, delete anything in either the Name or Value boxes again
11. to verify the changes; int the second box labled Name type or paste the following:

capability.principal

12. click the Search Preferences button
13. you should see both entries and their values that you just entered. There were no other entries on mine.
14. close the browser, and you're done.

TiddlyWiki should work correctly next time.

I made several mistakes before figuring this out, and I have several lines in about:config that I shouldn't. If anybody knows how to delete these I would appreciate it. In the mean time what I've done is paste the incorrect Name into the Name box and hit the Set Preference button with the Value field blank. It seems to work, bit I know it's wrong.