Renderer API — window.ow

The kernel injects window.ow into every document it loads. All calls from the renderer go through this object. It is a distinct surface from @owear/core, which is used in the main process.

Types for this object live in a scaffolded app's src/ow.d.ts, maintained by hand against this page.

Methods

ow.invoke

ow.invoke<T = unknown>(module: string, fn: string, ...args: unknown[]): Promise<T>

Calls a function of a native module. args are passed as a JSON array. Rejects with the native error message on failure. Rejects with Error('ow: timeout <module>/<fn>') if the kernel does not respond within 30 seconds.

const text = await ow.invoke<string>('fs', 'readText', '/etc/hostname')
const { filePaths } = await ow.invoke('dialog', 'showOpenDialog', { properties: ['openFile'] })

ow.invokeSync

ow.invokeSync(module: string, fn: string, ...args: unknown[]): unknown

Synchronous variant, implemented with a blocking XHR to ow-sync://.

⚠️ Blocks the renderer and risks reentrancy. Use only during bootstrap, before interactive state exists. Never call from event handlers.

const dark = ow.invokeSync('theme', 'isDark') as boolean

ow.readShared

ow.readShared(handle: { id: string; size: number }): Promise<ArrayBuffer>

Reads a shared-memory region published by the kernel and returns an ArrayBuffer served from the mmap. This is how payloads ≥ 256 KB avoid JSON/base64. The region is served through the ow-shm:// scheme.

const res = await ow.invoke<any>('fs', 'readFile', '/tmp/big.bin')
const bytes = res.__ow_shm ? await ow.readShared(res.__ow_shm) : decode(res.b64)

ow.on

ow.on(name: string, cb: (payload: unknown) => void): () => void

Subscribes to an event. Returns an unsubscribe function.

const off = ow.on('fs.watch', ({ watcherId, events }) => {})
off()

ow.emit

ow.emit(name: string, payload?: unknown): void

Sends an event from JS to the native layer and to other JS listeners in the same document.

ow.emitTo

ow.emitTo(targetWindowId: number, name: string, payload?: unknown): void

Directed window → window event.

ow.findInPage

ow.findInPage(text: string, opts?: { matchCase?: boolean; backwards?: boolean })
  : { matches: number; active: number }

A JS helper around window.find, returning match counts. For the native find controller (with options) use the window module in a renderer with the kernel, or webContents operations.

Globals

Schemes available from the WebView

DOM attributes

<div data-ow-drag>…</div>                       <!-- drag region -->
<button data-ow-no-drag>…</button>              <!-- excluded from drag -->
<div data-ow-resize="bottom-right">…</div>      <!-- manual resize handle -->

Resize edges: left | right | top | bottom | top-left | top-right | bottom-left | bottom-right.

Related

• Bridge and wire format.
• Renderers guide.