# Traversing arrays and objects in CoffeeScript

# The array and object we use for testing
arr = [1, 2, 3, 4, 5]
obj = {a: 1, b: 2, c: 3, d: 4, e: 5}


# 'in' has a different meaning in CoffeeScript than in JavaScript
# CS: element in array -> JS: array.indexOf(element) >= 0
console.log '5 in arr: ' + (5 in arr)
console.log '5 in obj: ' + (5 in obj)
console.log 'e in obj: ' + ('e' in obj)

# 'of' in CoffeeScript is the 'in' known in JavaScript
# CS: key of object -> JS: key in object
console.log '5 of arr: ' + (5 of arr)
console.log '5 of obj: ' + (5 of obj)
console.log 'e of obj: ' + ('e' of obj)

# Traverse through an array
# CS: for i in arr -> JS: for( var i; i < arr.length; i++ )
# CS: i -> JS: arr[i]
console.log 'i in arr'
for i in arr
	console.log i

# CS: i -> JS: i, where i is an index 
# This will return only results for keys that 
# are numbers and within the range of the index
console.log 'i in obj'
for i in obj
	console.log i

# CS: for i of arr -> JS for( i in arr )
# CS: i -> JS: i, where i is an object key
# Basically, the same as JS: for( i in Object.keys(arr) )
console.log 'i of arr'
for i of arr
	console.log i

# This is the CS version of JS' for( k in obj )
console.log 'k of obj'
for k of obj
	console.log k

# CS: k, v -> JS: k, obj[k]
console.log 'k, v of obj'
for k, v of obj
	console.log k + ': ' + v

# array.forEach is a method and thus behaves consistently
# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/forEach
console.log 'array.forEach(callback(v, k, arr))'
arr.forEach (element, index, array) ->
	if index == 0
		console.log 'arr == array: ' + (arr == array)
	console.log index + ': ' + element

# .forEach is only available for arrays, not for objects