Legacy data can be imported into a new Rails app by connecting a second database and mapping old tables and columns with Active Record models.

Combine multiple PDF files from the Linux command line with pdftk or pdfjam; convert works too, but often lowers quality and increases file size.

IE11 drops calc() inside the flex shorthand, breaking layouts that need percentage widths with gutters. Using flex-basis separately preserves the intended size.

CoffeeScript class methods use @ on the class definition and can be called from instances through @constructor or the class itself.

Upgrading Clearance can break existing logins when password hashes change from SHA1 to BCrypt, causing BCrypt::Errors::InvalidHash for legacy users.

MariaDB and MySQL version changes can alter query results despite sql_mode; aggregated date queries may switch from strings to Datetime, breaking existing applications.

Webpacker-only Rails deploys can fail on deploy:assets:backup_manifest because capistrano-rails expects Sprockets assets. Clearing that task avoids the missing manifest error.

Capistrano records successful deployments with branch, commit, release ID, and user, letting teams trace who shipped which revision and when.

Quick reference for replacing common jQuery DOM tasks with native browser APIs and handling event delegation gaps without jQuery.

Lost or overwritten files can sometimes be recovered after git accidents or failed undo actions by using RubyMine's Local History.

CSS line-height and vertical-align depend on font metrics and inline formatting, making text and element alignment less predictable than it seems.

Encoded email source can hide the plain HTML markup in Thunderbird. Opening a message in composition mode gives access to the HTML view.

git apply can place a diff onto HEAD, often replacing a rebase-and-merge workflow when reconstructing commits or working from a patch file.

Browser-based unit tests in a Rails app can run with Jasmine and Webpacker by separating test runner and spec packs; a /jasmine page makes the setup easy to open.

RSpec can freeze without output and ignore --backtrace or Ctrl-C; sending USR1 can print all thread backtraces from a running Ruby process.

Blank and missing values in JavaScript need explicit handling; Unpoly provides up.util.isBlank(), up.util.isPresent(), up.util.isMissing() and up.util.isGiven() for common and custom types.

json 1.8.3 fails to build on Ruby 2.5 because of removed C API constants; updating the gem resolves the native extension error.

Katapult reduced the effort of bootstrapping Rails apps, but its maintenance cost outweighed the gains and development has ended.

JavaScript truthiness makes 0 and "0" look blank, while _.isEmpty only fits collections. Custom _.isBlank and _.isPresent give human-friendly checks.

PostgreSQL offers native column types such as json and arrays that simplify data modeling in Rails and can replace awkward workarounds from MySQL.

Travis CI builds can break after Ubuntu image changes, causing PostgreSQL, MySQL, and Rails test failures. Pinning dist: trusty keeps the older environment until the setup is updated.