I want to know exactly what Facebook, Instagram, Messenger is doing for background Application update (App-Update)? I observed they are updating applications outside playstore is it without user intervention?
As Facebook, Instagram, Messenger are all hybrid apps so the code base consists of HTML, javascript and any accompanying images which are bundled together and distributed as part of a platform-specific binary(.apk /.ipa). Once published you can't change the native code(Java/Kotlin/Swift/Objective C) but you can change your CSS, javascript, and images by using Code push plugin and For react native you can use React native module of code push.