Javascript is one of the most popular languages
Javascript's recent versions are much more capable
Javascript debugging tools are built into many browsers (including Chrome and Safari)
Javascript has a wide collection of open source libraries for doing everything from building beautiful websites to adding animation
Javascript has a huge community of online support to help you as you learn
Javascript developers are in high demand (you can get a great job)
Javascript is now used on servers with Node.js (initially it was only run in browsers)
Javascript can be used to develop native mobile apps for both iOS and Android (using frameworks like react)