CoffeeScript CheetSheet#

Declaration

there is no vars, and no need to add ';' and the end

i = 10str = "hello world"[firstName, lastName] = ["kang", "wang"]

define a function, no need to add the keyword 'function', -> is enough

fn = (param) -  ...

Splats: define a function with multi parameters

fn = (parm1, parm1, params...) ->    ...params = ["value1", "value2", "value3", "value4"]fn(params)fn("value", params)fn("value", "value", params)

define an Array

arr = [   "element1"   "element2"]

define an object

obj =    first: 1   second:       second_1: 1      second_2: 2   third: 3$('.element').attr class: "active"

lexical scoping and variable safity.

outter = 10scope = ->   inner = 10

outter = 20 inner = 20

String Interpolation

mixin variable and function in string defination

str = "variable 1: #{var1}, function 1 returns: #{fn()}"str = "   today is Sunday   so tomorrow is    Monday"htmlTpl = """                  
Hello World
         """

Destructuring Assignment

[var1, var2] = [value1, value2]

use on object unapply

{firstName, lastName} = {firstName: "Kang", lastName: "Wang"}

use for a function multi-returns

location () ->      ["US", "LA", "Berkly"][county, province, city] = location() [start, end] = "hello, world".split ","

use to skip some useless bucket ...

[start, ..., end] = [1, 2, 3, 4, 5]

destructuring constructor

class Person   constructor: (options) ->   {@name, @age, @height} = optionstim = new Person age: 4

condition control

if else then

"do something" if trueif true and true    "do something"else    "do other things"if true then "do something" else "do other things"

for loop control

for loop while until

print ele for ele in [1, 2, 3, 4]prints i, ele for ele in [1, 2, 3, 4]print ele for ele in [1, 2, 3, 4] when ele / 2 != 1countDown = (num for num in [10 .. 1] by 2)

loop an object

prints k, v for k, v of kidprint ele until ele > 10print ele while ele > 10

do keywords

for filename in list   do (filename) ->      fs.readFile filename, (err, contents) ->         compile filename, contents.toString()for ele in [1, 2, 3, 4]   do print ele

try .. catch .. expression

try 	  fn(1)catch error	  errorfinally	  then

try .. catch .. expression

Array Operations

numSerials = [10 .. 0]start = numSerials[0..2]end = numSerials[0..-2]end = numSerials[..]umSerials[0..2] = [1, 2, 3]

use expression as much as possible

globals = (name for name of window)[0...10]

Existantial Operator ?, ?.

'?' means varaible is null or undefiend

solipsism = true if mind? and world?speed = 0speed ?= 15footprints = yeti ? "bear"

'?.' usef for assessing object attribute

kid.brother?.sister

switch when else

switch day 	when "Mon" then "" 	when "Tue" then "" 	else "WTF" day = switch day 	when "Mon" then "" 	when "Tue" then "" 	else "WTF"

object oriented

use => to bind this in scope

Account = (customer, cart) ->   @customer = customer   @cart = cart    $('.shopping_cart').bind 'click', (event) =>     @customer.purchase @cart Account2 = (customer, cart) ->   @customer = customer   @cart = cart    $('.shopping_cart').bind 'click', (event) ->     @customer.purchase @cart

bind function to an exists function

Array::map = ->   "..."

some sugar

chained comparasion

cholesterol = 127healthy = 200 > cholesterol > 60

block regular expression

OPERATOR = /// ^ (  ?: [-=]>             # function   | [-+*/%<>&|^!?=]=  # compound assign / compare   | >>>=?             # zero-fill right shift   | ([-+:])\1         # doubles   | ([&|<>])\2=?      # logic / shift   | \?\.              # soak access   | \.{2,3}           # range or splat) ///

embeded javascript

fn = `function fn() {}`

operators and alias in CoffeeScript

CoffeeScript	             JavaScript  is	                        ===  isnt	                        !==  not	                        !  and	                        &&  or	                        ||  true, yes, on	                true  false, no, off	            false  @, this	                    this  of	                         in  in	                   no JS equivalent  a ** b	               Math.pow(a, b)  a // b	               Math.floor(a / b)  a %% b	               (a % b + b) % b

multi etends example

moduleKeywords = ['extended', 'included']  class Trait 	@mixin: (obj) =>    		for key, value of obj when key not in moduleKeywords 			@::[key] = value		  		obj.with?.apply(@) 		this  	@with: (objs ...) -> 		@mixin obj for obj in objs   MongoDao = 	find: () -> console.log("find items in mongo")  	create: () -> console.log("delete item in mongo")  class UserDao extends Trait  	@with Daoable, MongoDao