set.coffee

groceryList = {}
groceryList['Bananas'] = true
groceryList['Apples'] = true
groceryList['Grapes'] = true
groceryList['Kiwis'] = true
groceryList['Pears'] = true
groceryList['Apples'] = true # dublicates will be ignored

console.log(Object.keys(groceryList).length == 5)
console.log(groceryList['Kiwis'] == true)

for key of groceryList
  console.log(key) if groceryList.hasOwnProperty(key)

console.log(Object.keys(groceryList).length == 5)
delete groceryList['Kiwis']
console.log(Object.keys(groceryList).length == 4)

for key of groceryList
  delete groceryList[key]
console.log(Object.keys(groceryList).length == 0)