I read book about Java script and I think that Java was updated to latest version and there are changes if compare it to old book and new version is that right? So how as developer I find right codes to compile them .
Javascript grows with updates, browsers rarely remove features…
Old code will still work and newer may not always be better…. 
@Shicksal - are you thinking about Java or JavaScript? They are both very different and behave differently when version differences come up 