8chan's javascript somehow detects when an image starts loading, how is that accomplished?
The thumbnail goes gray for a second, and then it gets replaced when the large image starts loading. I tried reading the source code but I can't figure it out. I tried just about every eventlistener along with mutation observers but nothing detects the point where the image starts loading. I can only detect when it finishes loading or when the HTML changes. Searching online gives me no answers either.