Sessionstore.js file pop-ups for download, then disappears

Question

My prob is related to this one https://support.mozilla.org/en-US/questions/967691 but it is a bit different. I didn't notice if MF uploads without any reason (I don't observe this till now) but a .js file popped up for download all of a sudden until I dll-ed other things from Sendspace. The dll dialog box with it disappeared before I could react. Later it wasn't listed in Downloads. I found it as I checked all MF folders for *.js and I saw only one was with the same date and hour as the file popped up and it was sessionstore.js. I have "Flash and Video Download 1.38" add-on which is listed as a possible prob in the thread I linked. I deleted this file and the .bak one as it is said in the other thread. Should I disable the add-on too?

Answer 1

The sessionstore.js file in your currently active profile folder is updated every time you navigate to a new window or tab, as often as every 15 seconds. It seems very unlikely that a website would want to download/replace this file -- the site couldn't accurately update it because it doesn't know your browser history. Unless it was some kind of strange attack that causes you to load windows and tabs of the site's choosing when you restart Firefox and restore your previous session. ??
In some cases, you may see a prompt to open/save a js or json file when there is a glitch with the background communications conducted by scripts in the page. Sometimes Google search users report this (e.g., [https://support.mozilla.org/en-US/questions/921535 Occasionally, when I try to do a Google search, numerous "opening search" pop-up windows appear.]). Unless you spot a pattern, it could be difficult to find the cause.