Create EventSource in Meta Spark Studio.

Subject.ts

import Reactive from 'Reactive';

export class Subject<T> {
  private readonly _signalSource: StringSignalSource;
  private readonly _eventSource: Omit<EventSource<T>, 'subscribe'> & { subscribe(callback: (args: T) => void): Subscription };

  constructor() {
    this._signalSource = Reactive.stringSignalSource(uuid());
    this._eventSource = this._signalSource.signal.monitor() as any;
    this._eventSource.subscribe = (callback: (value: T) => void) =>
      this._signalSource.signal.monitor().subscribe(({ newValue }) =>
        callback(JSON.parse(newValue).value)
      );
  }

  get eventSource() {
    return this._eventSource;
  }

  next(value: T) {
    this._signalSource.set(JSON.stringify({ value, id: uuid() }));
  }

  dispose() {
    this._signalSource.dispose();
  }
}

function uuid() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
    var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
}

Usage.ts

import Diagnostics from 'Diagnostics';
import Reactive from 'Reactive';
import TouchGestures from 'TouchGestures';

const subject = new Subject<void>();

subject.eventSource.take(1).subscribe(v => {
  Diagnostics.log(1)
})
  
subject.eventSource.skip(1).take(1).subscribe(v => {
  Diagnostics.log(2)
})

TouchGestures.onTap().subscribe(() => {
  subject.next()
})