For when you can't remember the difference between .each and .map, here's a reminder! It's written in Ruby, but the principle is the same in Javascript.

each-vs-map.rb

# In Ruby

# Array.each
# Iterate through each a collection unchanged

User.all.each do |user|
  puts user.email
  puts user.name
  puts
end

# => veganstraightedge@gmail.com
# => Shane Becker 
# => 
# => aki@example.com
# => Aki Braun
# => 

# Array.map
# Create a new collection by manipulating an original collection
# Optionally, iterate over the new one

emails = User.all.map{ |u| u.email }
puts emails

# => ["veganstraightedge@gmail.com", "aki@example.com"]

emails.each do |email|
  puts email 
end

# => veganstraightedge@gmail.com
# => aki@example.com