Regex to extract youtube video id Matches: http://youtu.be/ID http://www.youtube.com/watch?v=ID http://www.youtube.com/v/ID& http://www.youtube.com/embed/ID&

regex.rb

# normal regex with unnamed groups -> JS/PHP,Pearl
/(\/v\/|\/embed\/|watch?.*v=)([A-Za-z0-9\-_]*)|youtu\.be\/([A-Za-z0-9\-_]*)/

# normal regex with named groups
m = /(\/v\/|\/embed\/|watch?.*v=)(?<id>[A-Za-z0-9\-_]*)|youtu\.be\/(?<id>[A-Za-z0-9\-_]*)/
m.match("http://youtu.be/fat9235")[:id]
# -> fat9235



### Rails example usage
def youtube_link_tag(link, opts={})                                                                                                                                       
  options = { width: 280, height: 265 }                                                                                                                                   
  regex = /(\/v\/|\/embed\/|watch?.*v=)(?<id>[A-Za-z0-9\-_]*)|youtu\.be\/(?<id>[A-Za-z0-9\-_]*)/                                                                          
  return "" if link.blank?                                                                                                                                                
  id = link[regex, :id]                                                                                                                                                   
  return "" if id.blank?                                                                                                                                                  
  content_tag :div, class: "video-iframe" do                                                                                                                              
    content_tag :iframe, "", width: options[:width], height: options[:height], src: "//www.youtube.com/embed/#{id}?wmode=opaque", frameborder: 0                          
  end                                                                                                                                                                     
end