Downloading ".js" or ".html" files from untrusted sources in 2021 (or now) can lead to browser hijacking or malware installation.
Clients typically categorized "hacks" into modules, allowing users to toggle specific cheats: Combat Modules : Features like (automatically attacking nearby players) and eaglercraft hacks 188 2021
Forced the browser canvas to render maximum light values, completely eliminating darkness. The Cat-and-Mouse Game: Anti-Cheats and Patches Downloading "
Earlier hacks were easily detected. Modern hacks aim to mimic human movements to avoid detection by server-side anti-cheat. eaglercraft hacks 188 2021