What is the atlass file?

[AdrienLemaire]

Following your example

loader.add("map","path/to/your/map.json")
    .add("atlass", "path/to/your/atlass.png)
    .load(()=>{

        const mapData = app.loader.resources["map"].data;
        const atlas = app.loader.resources["atlass"].spritesheet;

        //build manualy from map data and atlass
        const stage = CreateStage(atlas, map);
      });

I added the json file exported from Tiled, and for the png file added the only tileset image exported with the map. But doing so, the app.loader.resources["atlass"].spritesheet is undefined.

Is the atlass file something else generated by a tool like texturepacker? In that case, is it supposed to have another json file with the same filename in the same directory ? I tried to look into it, but couldn't generate a texturepacker file from my Tiled file for free (cutting the file in 16x16 tiles seems to be a pro-only feature).

What would be the correct way to load only a tiled file ?

[eXponenta]

Atlass is source of textures.
Tiled lookup a textures by their names.
atlass should be a json spritesheet.
When is middleware used, it try to load images automatically by their url in atlas data.