Is it possible to read files in the Work directory from JavaScript?

[MSFS 2020] Questions & Community Discussions
1

I’m currently investigating building an in game panel which interfaces with an
in-proc wasm module and as part of this have a reasonable amount of local user
data (potentially a few KB) to read on the HTML/JS side. Is it possible to
read files saved in the work folder from JavaScript to save me sending this in
tiny chunks over L-Vars? If it isn’t possible right now, could this be
supported in the future?

2

I haven’t tried file access in javascript with the sim yet, so just a shot in
the dark:

      1. let rawFile = new XMLHttpRequest();
  2. rawFile.open("GET", "\work\filename.txt", true);
  3. rawFile.onreadystatechange = function() {
  4.   if (rawFile.readyState === 4) {
  5.     this.allText = rawFile.responseText;
  6.   }
  7. }
3

You also need to call rawFile.send() after building the request, but
unfortunately that results in the following error:

      1. [Error] Failed to load resource: the server responded with a status of 404 (Unable to process resource request) (work\test.json, line 0)

For what it’s worth, the code snippet you provided is essentially what
Utils.loadFile does internally. I tried a few different variants of the path
with no success:

      1. /work/test.json        (404)
  2. ./work/test.json       (404)
  3. coui://work/test.json  (Cross origin request error)
  4. work://test.json       (Cross origin request error)
4

Just to add for the benefit of others, this method works perfectly fine for
files that are embedded in the package, but files written to the work folder
from a wasm module can’t be read in this way unless there’s another path/API
that I haven’t found yet.

5

Hello Steve, As you mentioned in your last comments, only files embedded in
the package can be accessed through js at the moment. I’ve added a task about
giving access to the work directory in our backlog. I suggest you create an
idea about this feature so people can upvote it and we have a better idea of
how to prioritize it. Regards, Sylvain

6

necro alert, apologies - “this method works perfectly fine for files that are
embedded in the package” - is that correct? In my JS I’m trying to READ files
in the SimObject directory of my package and as far as I can tell Coherent is
treating the “html_UI” package directory as the root of the http access, so
there’s no access in JS outside of that directory (I’ve tried
“/…/SimObjects/…” but no success).

7

In JS you can access the entire VFS, which includes your package content
(except where it may conflict with another package).
/VFS/simobjects/airplanes/your-aircraft-name/panel/panel.xml