In vB you can set up a simple loop that runs through all the sub-directories in the directory and built up an object or array of the files or data that way - I don’t know JS well enough but perhaps there is a way to do that?
<psudoCode>
Count the sub directory number then
For i = 1 to i = subdirectory.number
Open sub directory
Get all the expressionmap data
Add data to big list of data
Next i
</psudoCode>