Upgrade ionic vs upgrade cordova


I’m new to ionic platform but I have been recently moved to a mobile dev team who uses ionic. We have a couple of ionic v2 apps with cordova 7xx. Reading on https://cordova.apache.org/docs/en/latest/guide/platforms/android/, i think we better upgrade cordova to v8 in order to support higher version of android. However, i am not sure if we have to or should upgrade ionic to v4 too. One note is that our app was written in js while most ionic examples i see today are in typescript, am i correct assuming that i don’t have to convert any js to typescript ?