Component Refs

Developer Agent Kit — documentation written for AI agents, readable by humans.

Refs provide access to DOM elements declared as interactive in the contract. They are the second parameter of the interactive constructor.

Single Refs

A ref maps to one DOM element:

# Contract
- tag: addToCart
  type: interactive
  elementType: HTMLButtonElement

// Component
.withInteractive(function MyComp(props, refs) {
    refs.addToCart.onClick(() => {
        // handle click
    });
})

Ref Methods

Refs provide type-safe access to the DOM element:

refs.submitButton.onClick(() => {
  /* ... */
});

// exec$ gives direct access to the element and current ViewState.
// Only use exec$ inside event handlers — never at top-level component
// creation or in effects, because elements don't exist yet at that point.
refs.submitButton.onclick(() => {
  refs.submitButton.exec$((element, viewState) => {
    element.disabled = viewState.isSubmitting;
  });
});

Collection Refs

When an interactive tag is inside a repeated sub-contract, the ref becomes a collection. In jay-html, collection refs use the $ suffix:

<div forEach="items" trackBy="id">
  <button ref="itemButton$">Click</button>
</div>

The $ is stripped from the name in the contract and component code:

# Contract
- tag: items
  type: sub-contract
  repeated: true
  trackBy: id
  tags:
    - tag: id
      type: data
      dataType: string
    - tag: itemButton
      type: interactive
      elementType: HTMLButtonElement

Collection Ref Methods

// Map over all items in the collection
const labels = refs.itemButton.map((proxy, viewState, coordinate) => {
  return viewState.name;
});

// Find a specific item
const target = refs.itemButton.find((viewState) => viewState.id === 'target-id');

// Find by coordinate
const target = refs.itemButton.find((viewState, coordinate) =>
  sameCoordinate(coordinate, ['item-2', 'itemButton']),
);

Element Types

Common element types for interactive tags:

Element Type	Use For
HTMLButtonElement	Buttons, clickable
HTMLAnchorElement	Links
HTMLInputElement	Text inputs, checkbox
HTMLSelectElement	Dropdowns
HTMLTextAreaElement	Multi-line text
HTMLFormElement	Forms
HTMLDivElement	Generic containers

Multiple element types (when the same ref may bind to different elements):

- tag: trigger
  type: interactive
  elementType: HTMLButtonElement | HTMLAnchorElement

Data + Interactive

A tag can be both data and interactive:

- tag: quantityInput
  type: [data, interactive]
  dataType: number
  elementType: HTMLInputElement

This generates both a ViewState field and a ref.

DOM access rules (Jay Stack pages)

Refs are the only supported path from TypeScript to elements Jay renders. Direct document access bypasses the framework and can break rendering, updates, and performance.

Do

• Declare elements in jay-html with ref="...".
• Drive overlays, lists, and visibility with ViewState (if, forEach, signal-backed bindings).
• Attach handlers with ref APIs: refs.myRef.onclick, oninput, onkeydown, etc.
• Use refs.myRef.exec$((element, viewState) => …) inside handlers for focus, scroll, measure, or native APIs.
• For drags: setPointerCapture on the ref element that received pointerdown, then listen on that element.

Avoid

• document.querySelector / getElementById to find template elements
• document.createElement + appendChild for UI that belongs in jay-html
• document.addEventListener('mousemove'|'mouseup') for drags (use pointer capture instead)

Rare document exceptions

Use only when no ref can exist, with an inline comment:

Case	Example
Offscreen processing	document.createElement('canvas') for image export
Coordinate hit-testing	document.elementFromPoint during cross-overlay drag
Tests	document.dispatchEvent in Vitest

Global shortcuts or paste: prefer a root shell ref (ref="appRoot") with capture listeners.

See also: .cursor/skills/jay-dom-refs/SKILL.md in the jay monorepo.

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About this document

This page is part of the Jay Stack Agent Kit — documentation generated from the framework source and written primarily for AI agents. The language and structure are optimized for machine consumption — expect precise, specification-style prose rather than narrative documentation. Learn more about the Agent Kit →