Learn SINATRA with Real Code Examples

require 'sinatra'

count = 0

get '/counter' do
    "<h2>Counter: #{count}</h2>
    <form method='post' action='/increment'>
        <button type='submit'>+</button>
    </form>
    <form method='post' action='/decrement'>
        <button type='submit'>-</button>
    </form>
    <form method='post' action='/reset'>
        <button type='submit'>Reset</button>
    </form>"
end

post '/increment' do
    count += 1
    redirect '/counter'
end

post '/decrement' do
    count -= 1
    redirect '/counter'
end

post '/reset' do
    count = 0
    redirect '/counter'
end

# Run with: ruby app.rb -p 4567

Demonstrates a simple Sinatra app with a counter using in-memory state and route handlers.