[lobrien]

Go is supposed to be a better C.

Scala is supposed to be a better Java.

JS is supposed to be popular.

EDIT: Go is intended to be a systems-programming language with an emphasis not only on runtime efficiency and concurrency, but additionally on such things as compilation speed.

Scala is intended to be a hybrid OO-functional language that is approachable by a broad class of mainstream programmers (i.e., Java programmers), with a type system considerably more sophisticated than Java. The emphasis is, I'd say, on a language that has long-term potential, at the cost of a somewhat problematic toolchain.

JavaScript's enormous advantages are that it is universally available, easy to approach, and flexible enough to support functional techniques.