craft-garnish

Development

Garnish — Craft CMS's built-in JavaScript UI toolkit for the control panel. Covers the class system (Garnish.Base.extend, init, setSettings, addListener, on/off/trigger, destroy), UI widgets (Modal, HUD, DisclosureMenu, MenuBtn, CustomSelect, ContextMenu, Select), drag system (BaseDrag, DragSort, DragDrop, DragMove), form widgets (NiceText, CheckboxSelect, MixedInput, MultiFunctionBtn), utilities (key constants, ARIA helpers, focus management), and Craft integration (GarnishAsset, webpack externals, Craft.* class pattern). Triggers on: Garnish.Base.extend, Garnish.Modal, Garnish.HUD, Garnish.DragSort, Garnish.DisclosureMenu, Garnish.ESC_KEY/RETURN_KEY, activate/textchange events, UiLayerManager, registerShortcut, trapFocusWithin, garnishjs, GarnishAsset, CpAsset, CP JavaScript, modal dialog, HUD popover, Craft.CP, Craft.Slideout, Craft.ElementEditor, onSortChange, onOptionSelect, onSelectionChange, aria-modal, focus trap, keyboard navigation CP, this.base(), window.Garnish, CP memory leak, event listener cleanup, jQuery .on() in CP. Always use when writing, editing, or reviewing JavaScript that runs in the Craft CP — plugin CP assets, custom field type JS, element index JS, CP webpack config, or code that imports garnishjs or references window.Garnish. Also trigger for CP accessibility, keyboard interactions, drag-sort behavior, or CP JS memory issues. Do NOT trigger for front-end JavaScript (Alpine, Vue, htmx) or Twig templates (craft-site).

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How to use this skill

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Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/development/craft-garnish/SKILL.md

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Garnish — Craft CMS Control Panel JavaScript Toolkit

Reference for Garnish, Craft CMS's built-in JavaScript UI framework. Covers the class system, UI widgets, drag interactions, form components, accessibility helpers, and integration with Craft's CP.

This skill is scoped to Garnish itself — the JavaScript library at src/web/assets/garnish/. For PHP-side plugin development (elements, controllers, services), see the craftcms skill. For CP template markup that Garnish widgets attach to, see the craftcms skill's cp.md reference.

Companion Skills — Load When Needed

craftcms — Load when the task involves PHP asset bundle classes, plugin architecture, or CP template markup that Garnish widgets attach to. Skip for pure JavaScript refactoring, Garnish API questions, or JS-only tasks.
craft-php-guidelines — Load only when editing PHP files (asset bundle classes, controllers that register JS). Skip for pure JS work.

Documentation

Garnish source: src/web/assets/garnish/src/ in the Craft CMS repository
No official external documentation exists — this skill IS the documentation.

Use WebFetch on Craft's class reference (https://docs.craftcms.com/api/v5/) when looking up PHP-side asset bundle registration.

Common Pitfalls (Cross-Cutting)

Using jQuery .on() directly instead of this.addListener() — listeners added via jQuery won't auto-clean on destroy(), causing memory leaks.
Forgetting this.base() when overriding destroy() — parent cleanup (listener removal, event teardown) gets skipped.
Using click instead of activate event on non-<button> elements — activate handles both click and keyboard (Space/Enter), making the UI accessible.
Fighting UiLayerManager by binding ESC directly — use Garnish.uiLayerManager.registerShortcut(Garnish.ESC_KEY, callback) so escape routes through the layer stack correctly.
Magic key code numbers instead of Garnish.ESC_KEY, Garnish.RETURN_KEY, etc. — constants are self-documenting and consistent.
Instantiating Garnish widgets before the DOM is ready — Garnish requires jQuery and all dependencies loaded first; in plugin assets, rely on CpAsset dependency chain.
Not calling destroy() when removing widgets — orphaned listeners accumulate, especially in slideouts and live preview where DOM is repeatedly created/destroyed.
Importing Garnish into webpack bundles instead of using the external — import Garnish from 'garnishjs' resolves to window.Garnish via webpack externals; bundling it duplicates 134KB.
Using deprecated Garnish.Menu instead of Garnish.CustomSelect — Menu is an alias kept for BC only.
Using deprecated Garnish.escManager or Garnish.shortcutManager instead of Garnish.uiLayerManager — the newer manager provides layer-aware keyboard routing that respects the modal/menu stack.

Reference Files

Read the relevant reference file(s) for your task. Multiple files often apply together.

Task examples:

"Create a modal dialog in a plugin's CP JS" → read class-system.md + ui-widgets.md
"Add drag-to-reorder to a custom field type" → read drag-system.md + class-system.md
"Build a custom CP widget class" → read class-system.md + integration.md
"Add a disclosure menu to a CP template" → read ui-widgets.md + integration.md
"Handle keyboard events in CP JavaScript" → read utilities.md + class-system.md
"Create an inline editor HUD" → read ui-widgets.md (HUD section)
"Make a selection interface for elements" → read ui-widgets.md (Select section)
"Set up a plugin's webpack config for Garnish" → read integration.md
"Custom element index class isn't loading" → read integration.md (Element Index JS Loading)
"Load element index JS with Vite" → read integration.md (Element Index JS Loading — Vite doesn't work for element index classes)
"Add ARIA attributes to a custom modal" → read utilities.md (ARIA & Focus section)
"Understand how Craft.CP extends Garnish" → read integration.md + class-system.md
"Build a multi-state submit button" → read integration.md (Form Widgets section)
"Add auto-growing textarea behavior" → read integration.md (Form Widgets section)

Reference	Scope
`references/class-system.md`	Garnish.Base, inheritance (extend/init/base), events (on/off/trigger), listeners (addListener/removeListener), settings, namespacing, enable/disable, destroy lifecycle
`references/ui-widgets.md`	Modal, HUD, DisclosureMenu, MenuBtn, SelectMenu, CustomSelect, ContextMenu, Select — constructor args, settings/defaults, methods, events, ARIA behavior
`references/drag-system.md`	BaseDrag, Drag, DragSort, DragDrop, DragMove — class hierarchy, settings/defaults, events, helper system, insertion points, scroll handling
`references/utilities.md`	Garnish namespace object, key constants, custom jQuery events (activate, textchange, resize), ARIA/focus management, geometry/hit testing, animation, form helpers, detection
`references/integration.md`	GarnishAsset PHP bundle, webpack externals, loading sequence, Craft.* class pattern, Twig JS blocks, form widgets (NiceText, CheckboxSelect, MultiFunctionBtn, MixedInput)