CoffeeScript

Must know

1. Variables
2. Safety closure
3. Functions, implicit return
4. No coercion issues is is alway ===
5. Loops, loop, for v in arr, for k, v of ob, for own k, v of ob
6. Binding function aka Fat arrow =>
7. Existential Operator foo?.bar
8. Everything is an expression

numbers = for i in [0..10]
  i * 2

1. Classes and prototypes

Nice things

1. List Comprehensions (i for i in [0..100] when i > 50)
2. Destructing Assignment {Foo} = require "bar", [host, port] = getConfig
3. Multiline strings. Regexp too.
4. and, or, is, isnt, not instead of ===, &&, || etc.1. String interpolation. "I have #{ variable }"
5. Array slicing numbers[numbers.length/2...numbers.length]