This script checks for changes in the list of 4k G-sync monitors that Jimm's sells.

jimms-4k-notifier.rb

#!/usr/bin/env ruby

require "nokogiri"
require "open-uri"

filename = "4k_monitors.txt"

old_names = File.readlines(filename).map(&:strip) rescue []

page = Nokogiri::HTML(open("https://www.jimms.fi/fi/Product/List/000-1HJ/oheislaitteet--naytot--g-sync?ob=6&fq=4k"))
product_names = page.css("#productlistdata .p_col_info .p_name").map {|e| e.text.strip }

added = product_names - old_names

if added.any?
  puts "New monitor%s discovered:" % (added.size == 1 ? "" : "s")
  puts added
  puts
end

removed = old_names - product_names

if removed.any?
  puts "Monitor%s disappeared from listing:" % (removed.size == 1 ? "" : "s")
  puts removed
end

if added.any? or removed.any?
  File.open(filename, "w") do |f|
    f.puts product_names
  end
end