Simple Ajax Sinatra example

actions.rb

require 'sinatra/json'

def get_click_data
    {
        count: Click.count,
        last_timestamp: Click.all.order('created_at DESC').first.created_at
    }
end

get '/' do
  erb :index
end

get '/num_clicks' do
  json get_click_data
end

post '/click' do
  puts params.inspect
  Click.create

  json get_click_data
end

application.js

$(document).ready(function() {

    var updateClicks = function(response) {
        var count = response.count;
        var timestamp = response.last_timestamp;

        var elements = $('<div>')
            .append($('<div>').addClass('count').text(count))
            .append($('<div>').addClass('timestamp').text(timestamp));
        $('#counter').html(elements);
    }
    


    $('button').on('click', function(event) {

        var data = {
            some_data: "whatever",
        }
        $.post('/click', data).done(updateClicks).fail(function(response) {
            console.log("ERROR!");
        });
    });
});