I doubt you'd be able to simulate an SD card without quite a lot of changes to the Espruino interpreter itself.
I'm not quite sure what you want to do, but you may be able to 'switch' an SD card away from the Raspberry Pi, so it can be accessed by the Espruino, then switch it back.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Hi Vicary,
I doubt you'd be able to simulate an SD card without quite a lot of changes to the Espruino interpreter itself.
I'm not quite sure what you want to do, but you may be able to 'switch' an SD card away from the Raspberry Pi, so it can be accessed by the Espruino, then switch it back.