Bus Class

A type-safe event bus for cross-component communication. Built on EventTarget, it enforces event types at compile time and supports automatic cleanup via AbortSignal.

Import

import { Bus } from '@jadis/core';

Creating a Bus

type AppEvents = {
  userLoggedIn: { id: string; name: string };
  themeChanged: 'light' | 'dark';
  notification: string;
};

const appBus = new Bus<AppEvents>();

Methods

register(event, callback, signal)

Registers a listener for a specific event. Outside a Jadis component, provide an AbortSignal for cleanup.

const controller = new AbortController();
appBus.register('userLoggedIn', (detail) => {
  console.log(`User ${detail.name} logged in`);
}, controller.signal);

Inside Jadis components, prefer this.onBus(bus, event, callback) instead.

emit(event, detail?)

Dispatches an event with optional detail:

appBus.emit('userLoggedIn', { id: 'abc123', name: 'Alice' });
appBus.emit('themeChanged', 'dark');
appBus.emit('notification', 'New message received');

Full example

import { Bus, Jadis } from '@jadis/core';

type AppEvents = {
  dataLoaded: string[];
  error: Error;
};

const bus = new Bus<AppEvents>();

const fetchData = async (): Promise<string[]> => ['ready'];

class LogPanel extends Jadis {
  static readonly selector = 'log-panel';

  onConnect(): void {
    this.onBus(bus, 'dataLoaded', (items) => {
      console.log(`Loaded ${items.length} items`);
    });

    this.onBus(bus, 'error', (error) => {
      console.error('Error:', error.message);
    });
  }

  templateHtml(): Node {
    return <div>Log Panel</div>;
  }
}

class DataFetcher extends Jadis {
  static readonly selector = 'data-fetcher';

  onConnect(): void {
    fetchData()
      .then((items) => bus.emit('dataLoaded', items))
      .catch((error) => bus.emit('error', error));
  }

  templateHtml(): Node {
    return <div>Data Fetcher</div>;
  }
}

LogPanel.register();
DataFetcher.register();

Outside Jadis components

Manage the AbortController manually:

const controller = new AbortController();
bus.register('dataLoaded', (items) => console.log(items), controller.signal);
controller.abort();

See also

• Cross-Component Communication