@effection/events

@effection/events

Helpers for working with events in Effection. These helpers work both with Node.js style EventEmitters (on/off) and with browser style EventTarget (addEventListeners/removeEventListener).

Usage

The once operation can be used to wait for an event to occur exactly once.

import { main } from '@effection/main';
import { once } from '@effection/events';

main(function* sayHello() {
  yield once(window, "DOMContentLoaded");
  console.log('Hello World!');
});

The on operation returns a subscription which can be used to loop over events:

import { main } from '@effection/main';
import { on } from '@effection/events';

main(function* sayHello() {
  let messages = yield on(window, "message");

  while(true) {
    let message = yield messages.next();
    console.log('Got message:', message);
  }
});

It is a common pattern, primarily in Node to have an event called error which has an error as its first argument. @effection/events includes a helper to make handling this situation convenient:

import { main } from '@effection/main';
import { once, throwOnErrorEvent } from '@effection/events';

main(function* sayHello() {
  let someSocket = createSocket();

  yield throwOnErrorEvent(someSocket);

  yield once(someSocket, "open");

  let messages = yield once(someSocket, "message");

  while(true) {
    let message = yield messages.next();
    console.log('Got message:', message);
  }
});