Singletons in CoffeeScript

singleton.coffee

# CoffeeScript makes this almost uniquely easy.
class Singleton
  instance = undefined
  
  @getInstance : ->
    instance ?= new @

# And a singleton class can be subclassed elegantly too.
class SingletonTest extends Singleton
  constructor : ->
    @property = 100

t1 = SingletonTest.getInstance()
console.log t1.property # -> 100
t1.property = 200

t2 = SingletonTest.getInstance()
console.log t2.property # -> 200