All of these can be made by using the app files manager that the DecSoft App Builder IDE provides to you. Take a look at the below animated GIF image, in which you can see how we add a new image to the app using the app files manager: that image is then ready to use.
You can add scripts by using their remote URLs, so they are not copied into the app files, but properly linked in the app HTML, in order to be used. Script files are copied into the "app/scripts/" directory path and propertly linked in the app HTML.
You can add styles by using their remote URls, so, like the remote scripts, they are not copied into the app files, but properly linked in the app HTML, in order to be used. Style files are copied into the "app/styles/" directory path and are properly linked in the ap HTML.
When you add other files from the Others tab of the files manager, for example, JSON or TXT files, these files are copied into the "app/files/" directory path, so you can reach it by using a path like: "app/files/my-file.json".
Last, but not least, you can add entire folders (and their subfolders) by using the Folders tab of the files manager. These folders are copied "as is" in the "app/files/" directory path, so you can find your files in a path like: "app/files/my-folder/my-file.json".