Skip to content

ExpressEmitter.md

Latest commit

 

History

History
74 lines (49 loc) · 1.86 KB

ExpressEmitter.md

File metadata and controls

74 lines (49 loc) · 1.86 KB

ExpressEmitter

Pattern-matching event emitter for route-like event names.

Import

import { ExpressEmitter } from '@stackpress/lib';

When To Use It

Use ExpressEmitter when event names carry parameters or wildcard segments. It extends EventEmitter with string-pattern and RegExp listeners plus extracted params and args.

API

Constructor

const emitter = new ExpressEmitter('/');

separator defaults to '/'.

Properties

Name Type Notes
separator string Segment separator used when building route fragments.
expressions Map<string, EventExpression> Registered pattern expressions.

Methods

Method Returns Notes
match(event) Map<string, EventMatch> Includes exact matches and computed expression matches.
on(eventOrRegExp, action, priority = 0) this Accepts exact strings, :params, *, **, or raw RegExp.
use(emitter) this Merges expression metadata and listeners.

Pattern Rules

  • :name captures one segment into event.data.params.name
  • * captures one segment into event.data.args
  • ** captures multiple segments into event.data.args
  • RegExp listeners keep pattern empty and expose match groups through data.args

The constants VARIABLE_NAME and EVENT_PATTERNS are also exported from the module for pattern parsing.

Example

import { ExpressEmitter } from '@stackpress/lib';

type Events = {
  [key: string]: [string];
};

const emitter = new ExpressEmitter<Events>();

emitter.on('user/:id', async value => {
  console.log(value);
});

await emitter.emit('user/42', 'loaded');

const match = emitter.match('user/42').values().next().value;
match?.data.params.id;

Related