Bind event stream into for-await-of

yield_on_events.js

const stream = new class {      // Mock event stream
  handler = null;
  async start() {
    while (true) {
      const ms = Math.random() * 100;
      await new Promise(resolve => setTimeout(resolve, ms));
      if (this.handler) this.handler(ms);
      if (ms < 10 && this.handler) this.handler(ms);
    }
  }
  onEvent(handler) {
    this.handler = handler;
  }
}

class Monitor {
  events = [];                  // store events
  resolve = () => {};           // resolves current outstanding promise
  constructor(handler) {
    handler(event => {          // binds event listener
      this.events.push(event);  // add event
      this.resolve();           // call resolve
    });
  }
  async *stream() {                             // generator
    while (true) {
      let event;
      while (event = this.events.shift())       // get and remove previous event
        yield event;                            // yield event
      await new Promise(r => this.resolve = r); // wait for next call to handler
    }
  }
}

// Bind event stream into monitor
const monitor = new Monitor(stream.onEvent.bind(stream));
stream.start();

// Stream events
for await (const event of monitor.stream()) {
  console.log('monitor', { event })
}