CoffeeScript has some nice feature, especially as compared to ES5, but I always found it a tad too clever. The fact that {} are optional in a bunch of places makes it very difficult for me to parse mentally.
Other weird coffeescript quirk: "x isnt y" is not semantically to "x is not y".
Other weird coffeescript quirk: "x isnt y" is not semantically to "x is not y".