CoffeeScript
CoffeeScript is a multi-paradigm programming language that can be converted to JavaScript when it's compiled. This ability allows developers to create JavaScript programs as their final product, but to write the programs in a language that uses a more convenient and robust syntax.
CoffeeScript facilitates both imperative and functional programming styles, and can be used as a scripting language. Its syntax incorporates many popular elements of Ruby, Haskell, and Python. For example, it uses whitespace to define code blocks, much like Python.
Since its official release in 2010, CoffeeScript has become extremely influential. Brendan Eich, the creator of JavaScript, has referenced it as an example of the future direction that JavaScript should take. At some large software development organizations such as Dropbox, CoffeeScript has replaced JavaScript completely.