WebSocket with readyState$ and readyState utility streams

Websocket.js

import { interval } from 'rxjs'
import { distinctUntilChanged, mapTo, share } from 'rxjs/operators'

export const WEBSOCKET_READYSTATES = {
    NOOP: null, // Unused in example, but useful to identify when a websocket doesn't exist (ie, not operational)
    CONNECTING: 0,
    OPEN: 1,
    CLOSING: 2,
    CLOSED: 3
}

export class Websocket extends WebSocket {
  get readyState$() {
    return interval(1).pipe(
      mapTo(this.readyState),
      distinctUntilChanged(),
      share()
    )
  }
  
  get connecting$() {
    return this.readyState$.pipe(
      filter(readyState => readyState === WEBSOCKET_READYSTATES.CONNECTING)
    )
  }
  
  get open$() {
    return this.readyState$.pipe(
      filter(readyState => readyState === WEBSOCKET_READYSTATES.OPEN)
    )
  }
  
  get closing$() {
    return this.readyState$.pipe(
      filter(readyState => readyState === WEBSOCKET_READYSTATES.CLOSING)
    )
  }
  
  get closed$() {
    return this.readyState$.pipe(
      filter(readyState => readyState === WEBSOCKET_READYSTATES.CLOSED)
    )
  }
}