Textareaの改行コードを確認するやつ

app.rb

require 'sinatra'

set :bind, '0.0.0.0'

get '/' do
  erb :index
end

post '/s' do
  text = params['textarea']
  # text.gsub!(/\n/, '<br>')
  ret_text = "<pre>#{text}</pre>"
  p ret_text
  ret_text
end

Gemfile

gem 'sinatra', '~> 2.1'

index.erb

<!-- 本来のパスは views/index.erb -->
<form action="/s" method="post">
  <label for="textarea">
    <textarea name="textarea" id="textarea" cols="30" rows="10"></textarea>
    <button type="submit">submit</button>
  </label>
</form>