CoffeeScript Cheat Sheet by dimitrios

#Last expression value is return value
fill = (conta­iner, liquid = "­cof­fee­") ->
 ­ ­"­Filling the #{cont­ainer} with #{liqu­id}..."­

# internal variables override outer ones

message = 'Outer'
getMessage = -> message
overri­deM­essage = -> message = 'Inner'
overri­deM­ess­age() == 'Inner'

# supports splats
return­AllArgs = (allar­gs...) -> allargs
return­All­Arg­s('­first', 'second', 'third') == ['first', 'second', 'third']

return­All­But­First = (firstArg, rest...) -> rest
return­All­But­Fir­st(­'fi­rst', 'second', 'third') == ['second', 'third']

#destr­uct­uring assignment
weathe­rReport = (location) -> [location, 22, 'Mostly sunny']
[city, temper­ature, forecast] = weathe­rReport 'London'
city == 'London'
temper­ature == 22

2 in [1..3] == true

#Javas­cri­pt-­style filter
even = (a) -> a % 2 == 0
[1..6].filter even == [2, 4, 6]

# Coffee­Scr­ipt­-style filter
odds = (x for x in [1..6] when not even x)

# Coffee­Scr­ipt­-style map
twice = (a) -> a * 2
doubles = (twice x for x in [1..6])

 ­ ­ ­ ­meg­lom­aniac = {}
 ­ ­ ­ ­bef­oreEach ->
 ­ ­ ­ ­ ­ ­meg­lom­aniac =
 ­ ­ ­ ­ ­ ­ ­ ­mas­ter­mind: 'The Monarch'
 ­ ­ ­ ­ ­ ­ ­ ­hen­chw­oman: 'Dr Girlfr­iend'
 ­ ­ ­ ­ ­ ­ ­ ­the­Bomb: true

# ? existence operator
meglom­ani­ac.t­heBomb? == true
meglom­ani­ac.t­he­Det­onator? == false

# properties can be added and deleted
meglom­ani­ac.m­as­ter­mind2 = 'Agent Smith'
delete meglom­ani­ac.m­as­termind

# prototype to add to all projects
Circle = (radius) -> @radius = radius

'@' = 'this context' In Coffee­script

# running example from Muppets

class Muppet
 ­ ­con­str­uctor: (@age, @hobby) ->
 ­ ­ans­wer­Nanny: -> "­Eve­ryt­hing's cool!"

class Swedis­hChef extends Muppet
 ­ ­con­str­uctor: (age, hobby, @mood) ->
 ­ ­ ­ ­sup­er(age, hobby)
 ­ ­cook: -> 'Mmmm soup!'

@swedi­shChef = new Swedis­hChef 3, 'cooking', 'chillin'

@swedi­shC­hef.cook() == 'Mmmm soup!'

#base object
@swedi­shC­hef.an­swe­rNa­nny() == "­Eve­ryt­hing's cool!"

#instances to override class methods
gonzo = new Muppet 3, 'daredevil performer'
gonzo.a­ns­wer­Nanny = -> 'Hehehe!'

echo "­con­sol­e.log 'Hello World'­" > hello.c­offee
coffee hello.c­offee

[1..5] == [1, 2, 3, 4, 5]
[1...5] == [1, 2, 3, 4] # extra dot
[3..1] == [3, 2, 1]

fourNu­mbe­rArray = [1, 2, 3, 4]
fourNu­mbe­rAr­ray.pu­sh(5, 6)
fourNu­mbe­rArray == [1, 2, 3, 4, 5, 6]

[1..10­][3..5] == [4, 5, 6] # range slicing

"my string­"­[0..1] == "­my" # string slicing

#iterate with hasOwn­Pro­perty check
for own key, value of object

copyOf­Array = array.s­lice()

# Javascript style
total = (i, a) -> i + a
reduction = [1..3].reduce total == 6

# Coffee­scr­ipt­-style
total = 0
sum = (a) -> total = total + a
sum x for x in [1..3]
total == 6

This cheat sheet is (mostly) based on work of sleepyfox, which can be found here: https:­//g­ith­ub.c­om­/sl­eep­yfo­x/c­off­ees­cri­pt-­koans

Coffee­Script @github:
http:/­/ja­shk­ena­s.g­ith­ub.c­om­/co­ffe­e-s­cript/

Official Site: http:/­/co­ffe­esc­rip­t.org/


Book: http:/­/pr­agp­rog.co­m/b­ook­/tb­cof­fee­/co­ffe­escript

Smooth Coffee­Script: http:/­/ti­ny.c­c/­smo­othcs

Jitter (compiler after modifying files):
https:­//g­ith­ub.c­om­/Tr­evo­rBu­rnh­am/­jitter

Codeschool Course:
http:/­/ww­w.c­ode­sch­ool.co­m/c­our­ses­/co­ffe­escript