Deeply compare 2 variables and returns true if they are the same, else false

isSame.coffee

isSame = (obj1, obj2) ->
  if obj1 is obj2
    yes
  else if obj1? and obj2?
    if (t = typeof obj1) isnt typeof obj2
      no
    else
      if t isnt 'object'
        no
      else
        if obj1 instanceof Array
          # compare arrays
          if obj1.length isnt obj2.length
            no
          else
            for v, i in obj1 when not isSame(obj2[i], v)
              return no
            yes
        else
          # compare objects own properties
          keys1 = (k for own k of obj1)
          keys2 = (k for own k of obj2)
          if isSame(keys1, keys2)
            for k in keys1 when not isSame(obj1[k], obj2[k])
              return no
            yes
          else
            no
  else
    # one or the other isn't null/undefined
    no