Notify by Lou

📣 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

Ƭ Emitter<Data>: Single<Data> extends Single<never> ? Function<[], void> : Unary<Data, void>

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

Type parameters

Name	Description
Data	Data type.

View source

---

EventListener

Ƭ EventListener<Data>: Single<Data> extends Single<never> ? Function<[], void> : Unary<Data, void>

Event listener unary function.

See

Unary

Type parameters

Name	Description
Data	Data type.

View source

---

EventRegistry

Ƭ 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

Name	Type	Description
Events	extends EventTypeDictionary	Event registry.

View source

---

EventTypeDictionary

Ƭ EventTypeDictionary: ReadOnlyRecord<string>

Dictionary of event name to event types.

See

ReadOnlyRecord

View source

Functions

broadcast

▸ broadcast<Events>(eventRegistry?): Object

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

Type parameters

Name	Type	Description
Events	extends Object	Event registry.

Parameters

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

Returns

Object

Object with emit and on functions.

Name	Type
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

▸ emit<Events>(eventRegistry): <Event>(event: Event) => Emitter<Events[Event]>

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

Type parameters

Name	Type	Description
Events	extends Object	Event registry.

Parameters

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

Returns

fn

Curried function with eventRegistry in context.

▸ <Event>(event): Emitter<Events[Event]>

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

Type parameters

Name	Type	Description
Event	extends string	Event name.

Parameters

Name	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

▸ on<Events>(eventRegistry): <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

Name	Type	Description
Events	extends Object	Event registry.

Parameters

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

Returns

fn

Curried function with eventRegistry in context.

▸ <Event>(event): (listener: EventListener<Events[Event]>) => () => undefined

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

Type parameters

Name	Type	Description
Event	extends string	Event name.

Parameters

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

Returns

fn

Curried function with eventRegistry and event in context.

▸ (listener): () => undefined

Listens for calls of the event in context of the eventRegistry in context.

Parameters

Name	Type	Description
listener	EventListener<Events[Event]>	Listener to be called when the event is emitted.

Returns

fn

Function to remove the listener from the eventRegistry.

▸ (): undefined

Returns

undefined

Example

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

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