Online markdown preview lets writers see formatting changes instantly, with or without GitHub Flavoured Markdown support.

Window functions in PostgreSQL support running totals, rankings, and per-group calculations without collapsing rows; common table expressions can simplify complex analytical queries.

Web typography choices strongly affect readability and visual hierarchy, and common mistakes can make text hard to scan or unbalanced.

Remove individual pages from Google search results on a site you control by using Webmaster Tools and the Google Index removal feature.

Compile .jst templates into JavaScript functions via the asset pipeline for rendering with JST[...], including EJS and Eco templates.

Multiple image-processing steps on a CarrierWave version can trigger extra MiniMagick commands; combining options into one process keeps them in a single mogrify call.

MySQL GET_LOCK provides a simple distributed mutex for ensuring only one instance runs across machines without creating lock rows.

jsonb in PostgreSQL 9.4 stores JSON differently from json and suits queries, indexing, and Rails 4.2 integration better for many use cases.

BEM-style selectors can be generated from plain-language Cucumber locators, reducing repetitive typing when mapping readable step text to CSS classes.

Enumerable#count returns the total number of elements, the number equal to a given value, or the number matching a block condition.

Array#flatten recursively removes nested arrays by default; an optional depth argument limits flattening to one level or any chosen level.

Updating selenium-webdriver can trigger UDPSocket.open argument errors on Ruby 1.8.7 when an incompatible backports version overrides core behavior.

Gem for instantly showing failing specs while continuing to run the rest of the suite, instead of aborting on the first failure.

Targeted database migrations in Rails use STEP and VERSION to run, redo, rollback, or revert a chosen migration without processing the full history.

tig status provides a keyboard-driven GUI for git add -p, letting you stage or unstage whole files, chunks, and individual lines.

Touch-capable browser detection is imperfect, but checking for touch events offers the best tradeoff when feature-based detection is needed instead of device detection.

CoffeeScript in checks array membership, not object properties; JavaScript in tests whether an object has a property. Use of for property lookup in CoffeeScript.

CSS block formatting contexts isolate floats and clearing within a container, preventing layout interference between separate sections and enabling reliable two-column layouts.

Table rows in LibreOffice Writer can break across pages and columns, making layouts harder to read and control. Disabling row breaks keeps each row together.

Use rspec -b to print a full backtrace for failing examples and make the origin of an error easier to trace.

Reverse lookup in a Ruby hash returns the first key for a given value, or nil when the value is absent. Hash#key is available in Ruby 1.9+.

git diff treats moved files as delete/add pairs by default, hiding renames in reviews. -M or --find-renames makes the diff show file moves instead.

Angular apps served from a subpath can break ui-router links in new tabs; a matching <base> href keeps generated URLs working.

Ruby library for simple Flickr API access with methods mapped to the official documentation and data returned in an intuitive format.