@ilokesto/overlay

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A small React overlay runtime built on top of @ilokesto/store.

This package provides a provider-scoped overlay core with a built-in host, item lifecycle management, and adapter injection. It is intentionally headless about modal or toast semantics so higher-level packages can build on top of the same runtime without leaking behavior into the core.

Features

• Provider-scoped runtime — no global singleton; each OverlayProvider has its own store
• Isolated contexts — createOverlayContext() for multiple independent overlay stacks
• Promise-based async overlays — display() returns a Promise that resolves after exit animation
• Two-phase dismiss — close() triggers animation, remove() actually unmounts
• Reject support — reject(id, reason) rejects the Promise on remove() for error flows
• Batch close — closeAll() transitions all overlays to closing for batch exit animation
• Adapter lifecycle hooks — onOpen, onClosing, onUnmount via useLifecycle
• Adapter plugins — Provider-level common policies (logging, analytics, accessibility)
• ID deduplication — open({ id }) is idempotent; no dangling promises
• Single-item subscription — useOverlayItem(id) with Object.is bailout
• Open before Provider mount — store.open() works without a mounted Provider

Table of Contents

• Installation
• Basic Usage
• Promise-Based Overlays
• Two-Phase Dismiss Lifecycle
• Rejecting an Overlay
• Closing All Overlays
• Overlay ID and Deduplication
• Opening Overlays Before Provider Mount
• Isolated Overlay Contexts
• Adapter Lifecycle Hooks
• Adapter Plugins
• API Reference
• Source Layout
• Development
• License

Installation

pnpm add @ilokesto/overlay react

or

npm install @ilokesto/overlay react

Basic Usage

import { OverlayProvider, useOverlay, type OverlayAdapterMap } from '@ilokesto/overlay';

const adapters: OverlayAdapterMap = {
  modal: ({ isOpen, close, useLifecycle, ...props }) => {
    useLifecycle({
      onOpen: () => { document.body.style.overflow = 'hidden'; },
      onUnmount: () => { document.body.style.overflow = ''; },
    });

    if (!isOpen) return null;

    return (
      <div role="dialog" aria-modal="true">
        <h1>{String(props.title)}</h1>
        <button onClick={() => close(true)}>Confirm</button>
      </div>
    );
  },
};

function ExampleButton() {
  const { display } = useOverlay();

  const handleClick = async () => {
    const result = await display<boolean>({
      type: 'modal',
      props: { title: 'Delete this item?' },
    });

    console.log(result); // true or undefined
  };

  return <button onClick={handleClick}>Open</button>;
}

export function App() {
  return (
    <OverlayProvider adapters={adapters}>
      <ExampleButton />
    </OverlayProvider>
  );
}

Promise-Based Overlays

display() returns a Promise<TResult | undefined> that resolves when the overlay is fully removed (after exit animation):

const confirmed = await display<boolean>({ type: 'modal', props: { ... } });
// confirmed === true  → user clicked confirm
// confirmed === false → user clicked cancel
// confirmed === undefined → overlay was removed without close

For fire-and-forget usage, use open() which returns just the id:

const id = open({ type: 'toast', props: { message: 'Hello' } });

Two-Phase Dismiss Lifecycle

The dismiss lifecycle has two phases, giving adapters full control over exit animation timing:

Step	Function	What happens
1	close(id, result)	Status transitions to closing. isOpen becomes false. Adapter plays exit animation.
2	remove(id)	Item is removed from the store. Promise resolves with closeResult.

The adapter receives both close and remove as props. It calls close() to trigger the animation, then remove() on animation end:

const adapter = ({ isOpen, close, remove }) => {
  return (
    <div
      className={isOpen ? 'fade-in' : 'fade-out'}
      onAnimationEnd={() => { if (!isOpen) remove(); }}
    >
      <button onClick={() => close(true)}>Confirm</button>
    </div>
  );
};

Rejecting an Overlay

reject(id, reason) transitions an overlay to closing (same as close), but when the adapter later calls remove(id), the display() Promise is rejected with the reason instead of being resolved.

This is useful when an overlay represents a flow that can fail — for example, a login dialog cancelled by a timeout:

function LoginButton() {
  const { open, reject, remove } = useOverlay();

  const handleLogin = () => {
    const id = open({ type: 'modal', props: { title: 'Sign in' } });

    setTimeout(() => {
      reject(id, new Error('Login timed out'));
      remove(id);
    }, 5000);
  };

  return <button onClick={handleLogin}>Sign in</button>;
}

The two-phase dismiss lifecycle is preserved: reject only transitions the status to closing; the adapter plays its exit animation and then calls remove(id), which is when the Promise actually rejects.

Closing All Overlays

closeAll() transitions every open overlay to closing in one call. Unlike clear(), it does not remove items from the store or settle promises — the adapter still controls the unmount timing for each overlay.

	closeAll()	clear()
Status	All open → closing	Items removed immediately
Items in store	Remains	Emptied
Promises	Pending (settled on remove)	Settled immediately
Use case	Batch exit animation	Emergency cleanup

function CloseAllButton() {
  const { closeAll } = useOverlay();
  return <button onClick={closeAll}>Close all</button>;
}

Overlay ID and Deduplication

When open() is called with an explicit id, the store guards against duplicates:

• If an overlay with the same id is already open (or closing), open() returns the existing OverlayRequest — the same id and the same Promise.
• No second item is added to the store.
• The Promise is not duplicated, so there is no dangling promise.

This makes open({ id, ... }) idempotent — calling it multiple times with the same id while the overlay is active has no side effect.

Once the overlay is removed (or cleared), the id is released and can be reused for a new overlay.

Opening Overlays Before Provider Mount

store.open() can be called before OverlayProvider is mounted — the item is stored immediately, and useSyncExternalStore picks it up on the Provider's first render. No event emitter is needed:

const store = createOverlayStore();

// Called before any Provider exists
store.open({ id: 'early', type: 'modal' });

// Later — the item renders on first mount
<OverlayProvider adapters={adapters} store={store}>
  <App />
</OverlayProvider>

Isolated Overlay Contexts

By default, OverlayProvider, useOverlay, useOverlayItems, and useOverlayItem all share a single React context. If you need multiple independent overlay stacks (e.g., a main app and an embedded widget), use createOverlayContext():

import { createOverlayContext } from '@ilokesto/overlay';

const mainOverlay = createOverlayContext();
const widgetOverlay = createOverlayContext();

// Each context has its own Provider, store, and hooks — fully isolated.
<MainApp>
  <mainOverlay.Provider adapters={adapters}>
    <Sidebar />
  </mainOverlay.Provider>
</MainApp>

<Widget>
  <widgetOverlay.Provider adapters={adapters}>
    <WidgetContent />
  </widgetOverlay.Provider>
</Widget>

Each context instance provides:

• Provider — context provider with built-in OverlayHost
• useOverlay — command API (open, close, closeAll, reject, remove, clear)
• useOverlayItems — subscribes to the full item list
• useOverlayItem(id) — subscribes to a single item

The default exports (OverlayProvider, useOverlay, etc.) are a pre-created instance of createOverlayContext() for backward compatibility.

Adapter Lifecycle Hooks

Adapters can register side-effect callbacks via the useLifecycle prop provided in OverlayRenderProps:

const modalAdapter: OverlayAdapterComponent = ({ useLifecycle, isOpen, close }) => {
  useLifecycle({
    onOpen: (id) => { document.body.style.overflow = 'hidden'; },
    onClosing: (id) => { /* status just transitioned to "closing" */ },
    onUnmount: (id) => { document.body.style.overflow = ''; },
  });

  if (!isOpen) return null;
  return <div role="dialog">...</div>;
};

The host calls hooks based on status transitions:

Hook	When	Guaranteed
onOpen(id, item)	First mount with status: "open"	Once per open
onClosing(id, item)	open → closing transition	Once per close
onUnmount(id)	Component unmount (after remove)	Once per lifecycle

If an adapter does not call useLifecycle, no hooks fire — the behavior is opt-in.

Adapter Plugins

Plugins provide Provider-level common policies — logging, analytics, or default accessibility behavior — without modifying each adapter individually:

import type { OverlayPlugin } from '@ilokesto/overlay';

const loggingPlugin: OverlayPlugin = {
  name: 'logging',
  onOpen: (id, item) => console.log('open', id, item.type),
  onClosing: (id, item) => console.log('closing', id, item.type),
  onUnmount: (id) => console.log('unmount', id),
};

<OverlayProvider adapters={adapters} plugins={[loggingPlugin]}>
  <App />
</OverlayProvider>

Priority Rule

• If an adapter registers a hook for a phase via useLifecycle, that hook takes priority — plugins are skipped for that phase.
• If an adapter does not register a hook for a phase, all plugins fire in registration order.

This means an adapter can override specific phases (e.g., custom focus trap) while plugins handle the rest (e.g., logging).

API Reference

createOverlayStore()

Creates a provider-scoped overlay store. Returns OverlayStoreApi with open, close, closeAll, reject, remove, clear, subscribe, getSnapshot, getInitialSnapshot.

createOverlayContext()

Creates an isolated React context. Returns { Provider, useOverlay, useOverlayItems, useOverlayItem }.

OverlayProvider

Context provider with built-in OverlayHost. Props: adapters, children, store?, plugins?.

useOverlay()

Returns { display, open, close, closeAll, reject, remove, clear }.

useOverlayItems()

Returns ReadonlyArray<OverlayItem> — the current overlay item list.

useOverlayItem(id)

Returns OverlayItem | undefined — subscribes to a single item by id with Object.is bailout.

Types

• OverlayStoreApi, OverlayProviderProps, OverlayItem, OverlayRequest, DisplayOptions, OverlayId, OverlayStatus, OverlayState
• OverlayAdapterComponent, OverlayAdapterMap, OverlayRenderProps, OverlayAdapterHooks
• OverlayPlugin
• OverlayContextInstance, OverlayContextValue
• UseOverlayReturn

Source Layout

src/
  core/
    createOverlayStore.ts
    createOverlayContext.tsx
    OverlayProvider.tsx
    OverlayHost.tsx
    useOverlay.ts
    useOverlayItems.ts
    useOverlayItem.ts
  contracts/
    adapter.ts
    overlay.ts
    plugin.ts
  index.ts

Responsibilities

src/core — runtime implementation:

• createOverlayStore.ts — store with open, close, closeAll, reject, remove, clear
• createOverlayContext.tsx — factory for isolated React contexts
• OverlayProvider.tsx — default context instance re-export (backward compatible)
• OverlayHost.tsx — renders items via adapters, calls lifecycle hooks on status transitions
• useOverlay.ts — command API hook
• useOverlayItems.ts / useOverlayItem.ts — subscription hooks with useSyncExternalStore

src/contracts — shared types:

• adapter.ts — OverlayRenderProps, OverlayAdapterComponent, OverlayAdapterMap, OverlayAdapterHooks
• overlay.ts — OverlayItem, OverlayStoreApi, DisplayOptions, OverlayProviderProps
• plugin.ts — OverlayPlugin

Dependency Direction

• core/* depends on contracts/*
• contracts/overlay.ts depends on contracts/adapter.ts
• contracts/adapter.ts does not depend on runtime code
• Adapter packages (modal, toast) should depend on @ilokesto/overlay
• @ilokesto/overlay should not import modal or toast implementations directly

The core owns lifecycle and hosting; adapter packages own semantics and presentation.

Development

pnpm install
pnpm run build
pnpm test

Build outputs are generated in the dist directory. Tests run with Vitest and @testing-library/react.

License

MIT