Case-insensitive address uniqueness in Rails needs a functional PostgreSQL index and custom model validation when built-in helpers do not support expression-based constraints.

Find Rails records with no associated rows, such as decks without cards or cards without a deck, using where.missing or left_joins.

Mailer previews often break when mailer code changes, and automated checks can catch missing updates before they reach development workflows.

Redirects in Rails use different default status codes in controllers and routes, and an unintended permanent redirect can affect browser behavior.

Open a JS Fiddle in fullscreen by appending /show to the URL; the viewer loads the fiddle without the editor chrome.

IRB’s multi-line completion can slow down input and make Backspace unreliable; --nomultiline or IRB.conf[:USE_MULTILINE] = false disables it while keeping Tab completion.

makandra_sidekiq 0.2.0 prevents Sidekiq from killing long-running jobs during shutdown by honoring the configured timeout and allowing jobs to requeue safely.

Reliable file-download testing in Capybara, including filename, content type, disposition, and text inspection across Selenium and Rack::Test without leaving the page.

Chrome and Safari consoles expose the selected DOM node, making Angular scope inspection fast when debugging selected page elements.

RSpec partial double verification blocks stubbing helper methods that come from Rails controllers; without_partial_double_verification or a spec config can disable it temporarily.

Changing RubyGems or Bundler versions on servers can leave deployed gems and binstubs incompatible; clearing the shared bundle path forces reinstall and avoids boot failures.

Relative asset URLs can work in Rails development but break after assets:precompile, because files are merged into public/assets and fingerprinted.

pre blocks can break out of nested flex layouts because flex items default to min-width: auto, causing overflowing code boxes and broken layouts.

ES2021 adds safer global string replacement, Promise.any(), logical assignment operators, numeric separators and WeakRef support in modern browsers.

Rails apps with multiple databases need separate test cleanup, or records bleed between specs and migrations. DatabaseCleaner can target each connection via a model-backed database key.

attribute? often checks presence like attribute.present?, but numeric values and associations behave differently; 0 can be false for ActiveRecord query attributes.

Unpoly event listeners can be limited to a single execution with { once: true } or up.off, useful for tests and callbacks that must not repeat.

Gem metadata can add source, bug tracker, changelog and MFA links to the RubyGems page, improving discoverability and security signals.

Inspect registered DOM event handlers in Chrome DevTools with getEventListeners(object) or the Event Listeners tab when debugging missing or duplicate listeners.

Need version or install-path details for a Ruby gem? gem info and Gem.loaded_specs provide gem metadata at the command line or during runtime.