jQuery can show or hide form sections based on select values, radio buttons, checkboxes, blank values, and _checked or _unchecked states.

Browser history navigation in Cucumber Selenium steps can be automated with window.history.back() through JavaScript when direct back-button control is needed.

Circular references make JSON.stringify fail with TypeError; a custom serializer or safe stringifier is needed to inspect or export object graphs.

Determining usable horizontal width on mobile is unreliable because device pixels, CSS pixels, and orientation differ across platforms. effectiveDeviceWidth() normalizes screen size with window.orientation and devicePixelRatio.

Positioning elements in JavaScript depends on window-relative and document-relative coordinates; mixing them causes misplaced layouts and incorrect measurements.

Small JavaScript library for drawing scalable graphics on the web; useful for custom charts and image manipulation widgets.

Inspired by a snippet of code in Oliver Steele’s legendary Functional library, here’s a lightweight tool to help keep track of JavaScript invocations. It works in Chrome, Safari, Firebug and IE8.

A lightweight JavaScript date library for parsing, manipulating, and formatting dates.

Detecting overflow in an element matters when layout must avoid hidden content and unwanted scroll bars; comparing scrollHeight and offsetHeight reveals whether content exceeds the visible area.

Selenium can miss browser events such as change during form input; a Cucumber step can fire jQuery-registered events manually with execute_script.

Hidden-element checks in Capybara can fail in Selenium when visibility is inferred too loosely. A JavaScript-based step works across Selenium, jQuery, Prototype, and Rack::Test.

Middleman static sites serve stable asset URLs by default, so cached JavaScript and CSS can stay outdated. :asset_hash adds fingerprinted paths to force cache refreshes.

Long, unwieldy dropdowns become easier to use with Chosen, a JavaScript enhancement available for jQuery and Prototype.

String helper extensions for Underscore.js add convenient text utilities to JavaScript projects.

JavaScript copy-to-clipboard support is moving into browsers through document.execCommand, reducing the need for Flash-based fallback buttons.

Speeds up navigation by keeping the page alive between link clicks, avoiding repeated JavaScript and CSS recompilation while replacing the body and title.

document.activeElement returns the currently focused DOM element and is useful for checking focus state in JavaScript or Selenium tests.

Determining whether an element is truly visible in the browser can differ across JavaScript libraries; jQuery and Prototype use different visibility rules.

A workaround for passing data from Sass to JavaScript through JSON, later extracted into a library.

Parallel Selenium features can time out when Capybara waits too little for browser-server interactions; a support file increases patience for @javascript scenarios.

Browser fullscreen handling is inconsistent across vendors, forcing boilerplate and event workarounds. screenfull provides a small wrapper for cross-browser fullscreen requests, exit, state, and change events.

Synthetic DOM events are awkward across browsers, especially for clicks and custom events. jQuery, Prototype, and Element.fire() offer simpler ways to simulate them.

JavaScript key binding library for handling single keys and key combinations in web apps.