Dispatcher

Legacy v1 docs

v1 is on security fixes only. See v2 docs for the current release.

Dispatcher extends the native EventTarget and adds helper methods for the event-driven communication system. Both Core and Devices extend this class.

import { Dispatcher } from "webserial-core";

Methods

on(type, callback)

Registers an event listener and marks the event type as active.

on(type: string, callback: EventListenerOrEventListenerObject): void

device.on("serial:connected", (event) => {
  console.log("connected", event.detail);
});

---

off(type, callback)

Removes a previously registered event listener.

off(type: string, callback: EventListenerOrEventListenerObject): void

const handler = (e) => console.log(e.detail);
device.on("serial:message", handler);
// later...
device.off("serial:message", handler);

---

dispatch(type, data?)

Synchronously dispatches a SerialEvent (a CustomEvent subclass). The data value becomes event.detail.

dispatch(type: string, data?: string | number | boolean | object | null): void

---

dispatchAsync(type, data?, ms?)

Dispatches an event after ms milliseconds (default 100).

dispatchAsync(type: string, data?: any, ms?: number): void

---

serialRegisterAvailableListener(type)

Registers a new event type so it appears in availableListeners. Called internally in the Core constructor — use it in your subclass to declare custom events.

serialRegisterAvailableListener(type: string): void

// inside your subclass constructor:
this.serialRegisterAvailableListener("my-custom-event");

---

removeAllListeners()

Removes every listener except internal:queue and resets all listening flags to false. Useful for cleanup.

removeAllListeners(): void

Properties

availableListeners

Read-only array of { type: string; listening: boolean } objects representing all registered event types.

get availableListeners(): { type: string; listening: boolean }[]

console.table(device.availableListeners);
// [
//   { type: "serial:connected",    listening: true },
//   { type: "serial:disconnected", listening: false },
//   ...
// ]