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Small-Scale Question Sunday for December 11, 2022

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

This is your opportunity to ask questions. No question too simple or too silly.

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Anyone know what's with a whole bunch of sites suddenly changing image download formats to jfif?

It's not the fault of the website, it's just that they don't specify a file extension at all, and so the browser appends one automatically.

On Firefox (likely the same for Chrome) the browser asks the operating system for the appropriate extension it wants for the MIME in question ("image/jpeg"). On Linux, this is read from /etc/mime.types. On Windows, this is read from the registry (HKEY_CLASSES_ROOT > MIME).

You're seeing .jfif because Microsoft recently decided that should be the primary extension for that file type. Note that this is actually the proper name for "jpeg" files, as the container format is actually called "JFIF" – "JPEG" is just the compression method it uses which has become the informal name for it.

Thank you! I knew it must have something to do with windows, because it happened on multiple sites at once and I haven't updated the browser in long enough that it doesn't work on most sites for a while.