Getting viewable text words via Nokogiri

You want the Nokogiri::XML::Node#inner_text method:

require 'nokogiri'
require 'open-uri'
html = Nokogiri::HTML(open 'http://stackoverflow.com/questions/6129357')

# Alternatively
html = Nokogiri::HTML(IO.read 'myfile.html')

text  = html.at('body').inner_text

# Pretend that all words we care about contain only a-z, 0-9, or underscores
words = text.scan(/\w+/)
p words.length, words.uniq.length, words.uniq.sort[0..8]
#=> 907
#=> 428
#=> ["0", "1", "100", "15px", "2", "20", "2011", "220px", "24158nokogiri"]

# How about words that are only letters?
words = text.scan(/[a-z]+/i)
p words.length, words.uniq.length, words.uniq.sort[0..5]
#=> 872
#=> 406
#=> ["Answer", "Ask", "Badges", "Browse", "DocumentFragment", "Email"]

# Find the most frequent words
require 'pp'
def frequencies(words)
  Hash[
    words.group_by(&:downcase).map{ |word,instances|
      [word,instances.length]
    }.sort_by(&:last).reverse
  ]
end
pp frequencies(words)
#=> {"nokogiri"=>34,
#=>  "a"=>27,
#=>  "html"=>18,
#=>  "function"=>17,
#=>  "s"=>13,
#=>  "var"=>13,
#=>  "b"=>12,
#=>  "c"=>11,
#=>  ...

# Hrm...let's drop the javascript code out of our words
html.css('script').remove
words = html.at('body').inner_text.scan(/\w+/)
pp frequencies(words)
#=> {"nokogiri"=>36,
#=>  "words"=>18,
#=>  "html"=>17,
#=>  "text"=>13,
#=>  "with"=>12,
#=>  "a"=>12,
#=>  "the"=>11,
#=>  "and"=>11,
#=>  ...

If you really want to do this with Nokogiri (and you can otherwise just use regex to strip tags), then you should:

1. doc = Nokogiri::HTML(open('url').read) #open-uri
2. strip all javascript and style tags with something like doc.search('script').each {|el| el.unlink}
3. doc.text