what is the FS reference in the Emscripten example ?

[kevzettler]

Hello I am importing BrowserFS into a another typescript project that also targets Emscripten. I am confused on the Emscripten example from the README:

/**
 * Mounts a localStorage-backed file system into the /data folder of Emscripten's file system.
 */
function setupBFS() {
  // Grab the BrowserFS Emscripten FS plugin.
  var BFS = new BrowserFS.EmscriptenFS();
  // Create the folder that we'll turn into a mount point.
  FS.createFolder(FS.root, 'data', true, true);
  // Mount BFS's root folder into the '/data' folder.
  FS.mount(BFS, {root: '/'}, '/data');
}

Where exactly does the FS refrence come from? in:

  FS.createFolder(FS.root, 'data', true, true);
  // Mount BFS's root folder into the '/data' folder.
  FS.mount(BFS, {root: '/'}, '/data');

That implies its some global or polly fill or something. I have thought it might be from BFSRequire and tried this in my code:

    const BFS = new BrowserFS.EmscriptenFS();
    // Mount the file system into Emscripten.
    const FS = BrowserFS.BFSRequire('fs');
    FS.mkdir('/emulator');
    FS.mount(BFS, {root: '/'}, '/emulator');

That fails because mount is not defined on FS

Furthermore this approach fails as well:

    const BFS = new BrowserFS.EmscriptenFS();
    // Mount the file system into Emscripten.
    BFS.mkdir('/emulator');
    BFS.mount(BFS, {root: '/'}, '/emulator');

because mkdir does not exist on BFS. So how do I get this magic FS into my typescript project?

[kevzettler]

I have learned this is a magic global injected by emscripten