stimulus

Original🇺🇸 English
Translated

Build Stimulus controllers from scratch through production. Full lifecycle - create, debug, test, optimize, integrate with Turbo. Covers targets, values, actions, outlets, and UI patterns.

6installs
Added on

NPX Install

npx skill4agent add faqndo97/ai-skills stimulus
<essential_principles>

How Stimulus Works

Stimulus is a modest JavaScript framework that connects JavaScript behavior to HTML via data attributes. It doesn't render HTML—it enhances existing HTML with interactivity.

1. HTML-First Philosophy

State lives in the DOM, not JavaScript. Controllers can be discarded between page changes and reinitialize from cached HTML. Design controllers to read state from data attributes and restore themselves on reconnection.

2. Convention Over Configuration

Stimulus uses predictable naming conventions:
  • Controller:
    data-controller="clipboard"
  • Targets:
    data-clipboard-target="source"
  • Actions:
    data-action="click->clipboard#copy"
  • Values:
    data-clipboard-url-value="/api/copy"
  • Classes:
    data-clipboard-supported-class="visible"
  • Outlets:
    data-clipboard-result-outlet="#result"

3. Lifecycle Awareness

Controllers have three lifecycle callbacks:
  • initialize()
    - Called once when controller is instantiated
  • connect()
    - Called when controller is connected to DOM (can happen multiple times with Turbo)
  • disconnect()
    - Called when controller is removed from DOM
Always clean up in
disconnect()
what you set up in
connect()
(timers, event listeners, observers).

4. Scope Isolation

Each controller only sees elements within its scope (the element with
data-controller
and its descendants). Targets must be within scope. Use outlets to communicate across controller boundaries.

5. Progressive Enhancement

Build HTML that works without JavaScript first. Use Stimulus to enhance, not replace. Check for API support before using features:
javascript
connect() {
  if ("clipboard" in navigator) {
    this.element.classList.add(this.supportedClass)
  }
}
</essential_principles>
<intake> **What would you like to do?**
  1. Build a new controller
  2. Debug an existing controller
  3. Add a feature to a controller
  4. Review controller(s) for best practices
  5. Optimize performance
  6. Implement a UI pattern (modal, dropdown, tabs, etc.)
  7. Integrate with Turbo
  8. Handle forms
  9. Something else
Wait for response before proceeding. </intake>
<routing> | Response | Workflow | |----------|----------| | 1, "new", "create", "build", "start" | `workflows/build-new-controller.md` | | 2, "broken", "fix", "debug", "crash", "bug", "not working" | `workflows/debug-controller.md` | | 3, "add", "feature", "extend", "modify" | `workflows/add-feature.md` | | 4, "review", "audit", "check", "best practices", "patterns" | `workflows/review-controller.md` | | 5, "slow", "optimize", "performance", "fast", "memory" | `workflows/optimize-performance.md` | | 6, "modal", "dropdown", "tabs", "accordion", "toggle", "UI", "pattern" | `workflows/implement-ui-pattern.md` | | 7, "turbo", "frames", "streams", "hotwire" | `workflows/integrate-turbo.md` | | 8, "form", "validation", "submit", "input" | `workflows/handle-forms.md` | | 9, other | Clarify, then select workflow or references |
After reading the workflow, follow it exactly. </routing>
<verification_loop>

After Every Change

  1. Does it connect? Check browser console for Stimulus connection messages
  2. Do targets resolve? Verify
    this.hasXxxTarget
    returns true
  3. Do actions fire? Add temporary console.log in action methods
  4. Does it clean up? Navigate away and back - no errors, no memory leaks
javascript
// Debug mode - add to application.js
application.debug = true
Report to the user:
  • "Controller connects: ✓"
  • "Targets found: X of Y"
  • "Actions working: ✓/✗"
  • "Ready for testing" </verification_loop>
<reference_index>

Domain Knowledge

All in
references/
:
Core APIs: architecture.md, targets.md, values.md, actions.md, outlets.md, classes.md Ecosystem: stimulus-use.md, ui-patterns.md Integration: turbo-integration.md Quality: testing-debugging.md, performance.md, anti-patterns.md </reference_index>
<workflows_index>

Workflows

All in
workflows/
:
FilePurpose
build-new-controller.mdCreate new controller from scratch
debug-controller.mdFind and fix bugs
add-feature.mdAdd functionality to existing controller
review-controller.mdAudit controllers for best practices
optimize-performance.mdProfile and speed up
implement-ui-pattern.mdBuild modals, dropdowns, tabs, etc.
integrate-turbo.mdWork with Turbo Frames/Streams
handle-forms.mdForm validation and submission
</workflows_index>