JS for Rails Developers (is jQuery OK?) Bruno Cunha, EarlyShares 

How’s your JavaScript? 

Agenda • Why? • AJAX • Unobtrusive JavaScript • Rails Helpers • Server-side Concerns • Turbolinks • Final Thoughts 

Why? JavaScript • Gut check • The best way • Client satisfaction jQuery • Easy 

AJAX Traditional Request-Response cycle • Client fetches full page and assets • Assemble everything together Asynchronous JavaScript and XML • Client fetches and renders data via JavaScript • Only update changed parts 

Unobtrusive JavaScript Separation of concerns • Avoid mixing presentation, layout, and behavior • Use data attributes to store private data 

Rails Helpers Form Options • Remote submits request using AJAX Link and Button Options • Also accept remote • Method changes request type • Confirm prompts the user after the request is made • Disable-with prevents multiple form submissions 

Server-side Concerns Serve appropriate response formats • Default is HTML • Options are JS, JSON, and XML 

Turbolinks • Makes apps faster by persisting assets and only rendering body changes • Other features include transition cache, opt-out, and progress bar • Uses custom page events, use jquery-turbolinks • 3rd-party plugins are problematic 

Final Thoughts User experience simply matters • Performance is easy and good Further Reading • Slack’s $2.8 Billion Dollar Secret Sauce - https://medium.com/@awilkinson/slack- s-2-8-billion-dollar-secret-sauce-5c5ec7117908 • Working with JavaScript in Rails - http://guides.rubyonrails.org/ working_with_javascript_in_rails.html • A Tour of Rails’ jQuery UJS - https://robots.thoughtbot.com/a-tour-of-rails-jquery-ujs • How I Use Turbolinks - https://pooreffort.com/blog/how-i-use-turbolinks/ 

Thank You! @bruncun