Ask HN: Should Learn/switch to JavaScript Programming (a Java Developer)

I've been a Java developer for the past 4 years. Recently I've been reading and learning a lot more about JavaScript also.Some, people say soon Java could get replaced by JavaScript. Would this ever happen? Are experienced people at HN hearing less of 'Java' projects than say 5 years ago? Will I get a good job if I switch to JavaScript or will I keep getting good opportunities if I continue in Java, esp as Java 8 has managed to include some concepts of functional programming. What will keep Java alive and moving forward in the coming years, other than legacy support codes and stable community contributions.