Not so much a new technology, but more of an established technology that is being used in new ways, Javascript really is one of the main areas that existing organisations need to develop their in-house development skills.
While many developers will say “sure I know how to code in Javascript”, their experience is limited to creating dynamic sections of a server-side driven web application. This is not the same as writing an application which is primarily Javascript, which is something that requires a greater understanding of how to structure a maintainable JS application.