Notify Reference

📣 Minimalistic Pub/Sub implementation.

Usage

📦 Node

Install @lou.codes/notify as a dependency:

pnpm add @lou.codes/notify
# or
npm install @lou.codes/notify
# or
yarn add @lou.codes/notify

Import it and use it:

import { broadcast } from "@lou.codes/notify";

const { emit, on } = broadcast<{ event: string }>();

const onEvent = on("event");
const offEvent = onEvent(console.log);

const emitEvent = emit("event");
emitEvent("Hello world 1"); // Logs "Hello world 1"
emitEvent("Hello world 2"); // Logs "Hello world 2"
offEvent();
emitEvent("Nope"); // Nothing happens

🦕 Deno

Import @lou.codes/notify using the npm: prefix, and use it directly:

import { broadcast } from "npm:@lou.codes/notify";

const { emit, on } = broadcast<{ event: string }>();

const onEvent = on("event");
const offEvent = onEvent(console.log);

const emitEvent = emit("event");
emitEvent("Hello world 1"); // Logs "Hello world 1"
emitEvent("Hello world 2"); // Logs "Hello world 2"
offEvent();
emitEvent("Nope"); // Nothing happens

🌎 Browser

Import @lou.codes/notify using esm.sh, and use it directly:

<script type="module">
	import { broadcast } from "https://esm.sh/@lou.codes/notify";

	const { emit, on } = broadcast();

	const onEvent = on("event");
	const offEvent = onEvent(console.log);

	const emitEvent = emit("event");
	emitEvent("Hello world 1"); // Logs "Hello world 1"
	emitEvent("Hello world 2"); // Logs "Hello world 2"
	offEvent();
	emitEvent("Nope"); // Nothing happens
</script>

Useful links

• 📝 Documentation: TypeDoc generated documentation.
• ⏳ Changelog: List of changes between versions.
• ✅ Tests Coverage: Coveralls page with tests coverage.

Type Aliases

Emitter<Data>

type Emitter<Data>: Single<Data> extends Single<never> ? () => void : Unary<Data, void>;

Emitter function (when data is never it doesn’t take any arguments).

Type parameters

Type parameter	Description
Data	Data type.

View source

---

EventListener<Data>

type EventListener<Data>: Single<Data> extends Single<never> ? () => void : Unary<Data, void>;

Event listener unary function.

See

Unary

Type parameters

Type parameter	Description
Data	Data type.

View source

---

EventRegistry<Events>

type EventRegistry<Events>: { readonly [Event in keyof Events]?: ReadOnlyArray<EventListener<Readonly<Events[Event]>>> };

Registry of event names to array of listeners.

See

• EventListener
• EventTypeDictionary

Example

const eventRegistry = {
	example: [() => console.log("example called")],
};

Type parameters

Type parameter	Description
Events extends EventTypeDictionary	Event registry.

View source

---

EventTypeDictionary

type EventTypeDictionary: ReadOnlyRecord<string>;

Dictionary of event name to event types.

Example

const example = {
	eventName: TypeOfEvent,
} satisfies EventTypeDictionary;

See

ReadOnlyRecord

View source

Functions

broadcast()

function broadcast<Events>(eventRegistry: EventRegistry<Events>): object;

Creates a new “broadcast” object, which has emit and on with a shared eventRegistry.

Type parameters

Type parameter	Description
Events extends Readonly<Record<string, unknown>>	Event registry.

Parameters

Parameter	Type	Description
eventRegistry	EventRegistry<Events>	Optional record of event names mapped to an array of listeners.

Returns

object

Object with emit and on functions.

Member	Type	Value
emit	<Event>(event: Event) => Emitter<Events[Event]>	…
on	<Event>(event: Event) => (listener: EventListener<Events[Event]>) => () => undefined	…

Example

const { emit, on } = broadcast<{ event: string }>();
const off = on("event")(console.log);
emit("event")("Hello world"); // Logs "Hello world"
off();
emit("event")("Nope"); // Nothing happens

View source

---

emit()

function emit<Events>(
	eventRegistry: EventRegistry<Events>,
): <Event>(event: Event) => Emitter<Events[Event]>;

Creates a curried function to emit events for listeners of the given eventRegistry.

Type parameters

Type parameter	Description
Events extends Readonly<Record<string, unknown>>	Event registry.

Parameters

Parameter	Type	Description
eventRegistry	EventRegistry<Events>	Record of event names mapped to an array of listeners.

Returns

Function

Curried function with eventRegistry in context.

Creates a curried function to emit an event of the eventRegistry in context.

Type parameters

Type parameter	Description
Event extends string | number | symbol	Event name.

Parameters

Parameter	Type	Description
event	Event	Event name (has to be a valid key of the eventRegistry).

Returns

Emitter<Events[Event]>

Curried function with eventRegistry and event in context.

Example

const eventRegistry = {};
const emitRegistry = emit(eventRegistry);
const emitEvent = emitRegistry("event"); // 👈🏻 You are here
emitEvent("data");

Example

const eventRegistry = {};
const emitRegistry = emit(eventRegistry); // 👈🏻 You are here
const emitEvent = emitRegistry("event");
emitEvent("data");

View source

---

on()

function on<Events>(
	eventRegistry: EventRegistry<Events>,
): <Event>(
	event: Event,
) => (listener: EventListener<Events[Event]>) => () => undefined;

Creates a curried function to listen for calls to an event in the passed eventRegistry.

Type parameters

Type parameter	Description
Events extends Readonly<Record<string, unknown>>	Event registry.

Parameters

Parameter	Type	Description
eventRegistry	EventRegistry<Events>	Record of event names mapped to an array of listeners.

Returns

Function

Curried function with eventRegistry in context.

Creates a curried function to listen for calls to an event of the eventRegistry in context.

Type parameters

Type parameter	Description
Event extends string | number | symbol	Event name.

Parameters

Parameter	Type	Description
event	Event	Event name (has to be a valid key of the eventRegistry).

Returns

Function

Curried function with eventRegistry and event in context.

Parameters

Parameter	Type
listener	EventListener<Events[Event]>

Returns

Function

Returns

undefined

Example

const eventRegistry = {};
const onRegistry = on(eventRegistry);
const onEvent = onRegistry("event"); // 👈🏻 You are here
const offEvent = onEvent(() => console.log("event called"));
emit(eventRegistry)("event")(); // Logs "event called"
offEvent();
emit(eventRegistry)("event")(); // Nothing happens

Example

const eventRegistry = {};
const onRegistry = on(eventRegistry); // 👈🏻 You are here
const onEvent = onRegistry("event");
const offEvent = onEvent(() => console.log("event called"));
emit(eventRegistry)("event")(); // Logs "event called"
offEvent();
emit(eventRegistry)("event")(); // Nothing happens

View source