Guide

Installation

1 npm install @xpulse/event --registry=https://npm.xpulse.one

Quickstart

1 import event from '@xpulse/event';
2  
3 // Listen
4 event.on('app:ready', (data) => {
5     console.log('App ready:', data.env);
6 });
7  
8 // Emit
9 event.emit('app:ready', { env: 'production' });

Listening

1 // Listen permanently
2 event.on('page:ready', (data) => {
3     console.log(data.lang);
4 });
5  
6 // Listen once – handler is automatically removed after first call
7 event.once('project:ready', (data) => {
8     console.log('Project loaded:', data.name);
9 });
10  
11 // Stop listening
12 const handler = (data) => { ... };
13 event.on('page:ready', handler);
14 event.off('page:ready', handler);

Emitting

1 event.emit('page:ready', { lang: 'en', route: '/privacy/' });

Payload is optional – an event can be emitted without data:

1 event.emit('app:stopping');

Registration (optional)

Events can optionally be registered for documentation purposes – this is not required before calling emit().

1 event.register('page:ready', {
2     description: 'Page rendered, i18n can take over',
3     emittedBy:   '@xpulse/project',
4     payload:     '{ lang: string, route: string }',
5 });

Emitting an unregistered event works fine – it just won't appear in event.list().

Introspection

1 // Show all registered events
2 event.list();
3 // → [
4 //     { name: 'page:ready', description: '...', emittedBy: '...', listeners: 2 },
5 //     { name: 'app:ready',  description: '...', emittedBy: '...', listeners: 1 },
6 //   ]
7  
8 // Active listeners for an event
9 event.listeners('page:ready');
10 // → [ [Function: handler1], [Function: handler2] ]
11  
12 // Listener count
13 event.listenerCount('page:ready');
14 // → 2

1	import event from '@xpulse/event';
2
3	// Listen
4	event.on('app:ready', (data) => {
5	console.log('App ready:', data.env);
6	});
7
8	// Emit
9	event.emit('app:ready', { env: 'production' });

1	// Listen permanently
2	event.on('page:ready', (data) => {
3	console.log(data.lang);
4	});
5
6	// Listen once – handler is automatically removed after first call
7	event.once('project:ready', (data) => {
8	console.log('Project loaded:', data.name);
9	});
10
11	// Stop listening
12	const handler = (data) => { ... };
13	event.on('page:ready', handler);
14	event.off('page:ready', handler);

1	event.register('page:ready', {
2	description: 'Page rendered, i18n can take over',
3	emittedBy: '@xpulse/project',
4	payload: '{ lang: string, route: string }',
5	});

1	// Show all registered events
2	event.list();
3	// → [
4	// { name: 'page:ready', description: '...', emittedBy: '...', listeners: 2 },
5	// { name: 'app:ready', description: '...', emittedBy: '...', listeners: 1 },
6	// ]
7
8	// Active listeners for an event
9	event.listeners('page:ready');
10	// → [ [Function: handler1], [Function: handler2] ]
11
12	// Listener count
13	event.listenerCount('page:ready');
14	// → 2