When it comes to coding languages, the best advice (that's tough to follow) is to pick one and stick with it. If you flip between languages or try to learn more than one at a time, you'll quickly find yourself overwhelmed and unable to get past the initial roadblocks.
Javascript is a powerful scripting language that runs in browsers. With the creation of Node, people have begun running JavaScript on servers and using it to create "native" apps that run outside of browsers. Javascript has exploded in popularity over the last few years.