... I don't understand why you put so much '509' code for all of them....
NaitLee: "I used a setInterval() in Takeback to load a few images (append an img element) at a time."
But, I didn't figure that out, so new Throwback does the tiny delays a little differently.
The purpose is same:
Single thread server with Multiple users.
If a nonstop stream of images to one user, other users can't get file list, server owner can't use UI.
However,
If we put in tiny delays between images, other users get the file list and server UI stays alive.
Also useful for less # requests per second.
P.S.
After that, NaitLee updated Takeback to a live preview, which is 1 photo a time and works really well on home connections.
So, the problem does not relate (does not happen) to the current version of Takeback.