Sinatra App for Demo JavaScript

app.rb

require 'sinatra'
require 'erubis'
require 'json'

get '/index' do
  erb :index
end

get '/data.json' do
  sleep 10

  content_type :json

  {
    :key1 => 'value1',
    :key2 => 'value2'
  }.to_json
end