events

A simple package to Emit and Listen events in Janis Services.

async/await

Important: Since 0.2.0 async callbacks are allowed, on() and once() accepts async functions and emit() will wait when await is used.

Emit

You can easily emit a new event using the static method async emit(eventName, ...args).

'use strict';

const Events = require('@janiscommerce/events');

await Events.emit('some-random-event', 'foo', 'bar');

Listen every time

To create listener for an event you should call the static method on(eventName, callback).

The callback will be called every time the event was emitted.

'use strict';

const Events = require('@janiscommerce/events');

Events.on('some-random-event', async (...args) => {
	// do some serious stuff with the args
});

Listen one time only

To create listener that is only called once should register the listener with the static method once(eventName, callback).

The callback will be called only the first time the event was emitted.

'use strict';

const Events = require('@janiscommerce/events');

Events.once('one-time-event', async (...args) => {
	// do some serious stuff with the args
});

Remove listeners

To remove listener of an event previously registered you should use the static method off(eventName).

This will remove all listeners (clean all callbacks): registered with on() or once()

'use strict';

const Events = require('@janiscommerce/events');

Events.on('my-event', async () => {
	console.log('my-event occurred!!!')
});

Events.once('my-event', async () => {
	console.log('my-event occurred for the first time!!!')
});

await Event.emit('my-event');
// expected output: my-event occurred!!!
// expected output: my-event occurred for the first time!!!

await Event.emit('my-event');
// expected output: my-event occurred!!!

Events.off('my-event');

await Event.emit('my-event'); // no output expected

Remove all listeners

To remove all listener registered you should use the static method off().

'use strict';

const Events = require('@janiscommerce/events');

Events.on('my-event', async () => {
	console.log('my-event occurred!!!')
});

Events.once('my-other-event', async () => {
	console.log('my-other-event occurred for the first time!!!')
});

await Event.emit('my-event');
// expected output: my-event occurred!!!
await Event.emit('my-event-event');
// expected output: my-other-event occurred for the first time!!!

Events.off();

await Event.emit('my-event'); // no output expected
await Event.emit('my-event-event'); // no output expected