How to access data from .write() in opencascade.js

I'm trying to access my data from my exported step file in opencascade.js.

I used this example

and updated the library.js like this to export a step-file:

var writer = new openCascade.STEPControl_Writer_1();
var progressRange = new openCascade.Message_ProgressRange_1();
writer.Transfer(reader.OneShape(), openCascade.STEPControl_StepModelType.STEPControl_AsIs, true, progressRange);
no errors are thrown, but I dont know how to access the data now.

I updated this sandbox too:

the library.js can be found here:

src/demos/bottle - basic/library.js