The Language of the Web
Server and Client
This is a huge benefit and can save time over learning two separate languages. Being able to reuse knowledge on both ends of software has swayed many companies to start using Node. It also means you as a developer can focus less on learning a new language and more on the aspects of back-end development, such as database management and security issues.
A Maturing Ecosystem
A Large Community
Having a large community around a language means that support is always close at hand. This makes it both easy to learn as well as find support when issues inevitably crop up. It also lends a lot of assurance that a language will continue to be popular, as large communities lend a certain momentum to keeping a language alive and relevant.