Time controlled image replacements

[Ian Meredith]

Hi, I am working on a homepage that includes a tile that links to some form news/newsletter. The nature of such things is they never get clicked on unless there is clear evidence that the linked page has been refreshed.

My thinking is that I shall have a static gif image and an animated version that alerts users to a recent change. The animated variant would be automatically swapped out for the static image after a given interval - say 3 days.
Can JavaScript interrogate the revision date of a file and specifically the file it is contained within? If not, perhaps I could insert a date variable in the build if such is possible within a script and then parse it to create the variable values in the script?

I am not myself a JavaScript coder so this is all going to be string together from what I can find on the web if possible at all. Any thoughts - or dare I ask: sample code?!

Ian