Events and State

Import the APIs on this page from @makoojs/core.

createObserverHub()

Creates a hub for subscribing to and emitting task lifecycle events.

Type

function createObserverHub(logger?: ILogger): ObserverHub;

Parameters

• logger: optional ILogger. A Logger is created when omitted.

Returns

Returns ObserverHub:

Method	Returns	Description
on(event, hook)	() => void	Registers a hook for an event
onTask(taskId, event, hook)	() => void	Registers a task-specific hook
onAny(hook)	() => void	Registers a hook for every event
off(event, hook?)	void	Removes event hooks
offTask(taskId, event?, hook?)	void	Removes task hooks
offAny(hook)	void	Removes a global hook
clear()	void	Removes all hooks
hasHooks(event?)	boolean	Checks whether any or a specific event has hooks
emit(event)	void	Emits an event
emitOnTask(taskId, event)	void	Emits an event for a task

Task events run task hooks, same-name event hooks, and onAny() hooks in that order. stopPropagation() prevents the next group from running. stopImmediatePropagation() also stops the remaining hooks in the current group. If a hook throws, the error is logged and the other hooks continue.

Example

import { createMakoo, createObserverHub, listen } from '@makoojs/core';

const observer = createObserverHub();
observer.on('listener:attached', (event) => {
  console.log('Listener attached:', event.taskId);
});

createMakoo({ observer }).start([
  listen({
    id: 'page-click',
    listenAt: 'body',
    type: 'click',
    callback: (event) => console.log(event.target)
  })
]);

createActivityStore()

Creates readable, subscribable, and writable state.

Type

function createActivityStore<T>(initialValue: T): {
	get(): T;
	subscribe(listener: (value: T) => void): SignalUnsubscribe;
	set(value: T): void;
	update(updater: (value: T) => T): void;
};

Parameters

• initialValue: the initial state value.

Returns

Returns an object with get(), subscribe(), set(), and update().

Details

subscribe() listens for future changes; use get() to read the current value. set() and update() compare values with Object.is() and notify subscribers when the value changes.

Example

import { createActivityStore } from '@makoojs/core';

const active = createActivityStore(true);
active.subscribe((value) => {
	console.log(value);
});

active.set(false);
active.update((value) => !value);

Observer types

type ObserveEventName = (typeof OBSERVE_EVENT_NAMES)[number];

type ObserveEvent = {
	name: ObserveEventName;
	ts: number;
	taskId?: string;
	kind?: 'component' | 'listener';
	injectAt?: string;
	status?: 'idle' | 'pending' | 'active';
	durationMs?: number;
	error?: unknown;
	preStatus?: 'idle' | 'pending' | 'active';
	meta?: Record<string, unknown>;
};

type ObserveHook = (
	event: ObserveEvent,
	ctrl: {
		stopPropagation(): void;
		stopImmediatePropagation(): void;
	}
) => void;

type LifecycleHookMap = Partial<
	Record<ObserveEventName, ObserveHook | ObserveHook[]>
>;

Signal types

type SignalUnsubscribe = (() => void) | { unsubscribe(): void };

type ActivitySignalSource<T = boolean> = {
	get(): T;
	subscribe(listener: (value: T) => void): SignalUnsubscribe;
};

type ActivitySignalSubscribable<T = boolean> = ActivitySignalSource<T>;