best practice for queue

[nblfikr]

I new in Rxjs. I spend several day learn it, and now trying to implement a queue sending message with it. In my code i want to send a message every 5 seconds, like this:

interval(5000)
.pipe(
  map(() => {
    if (this._queue.length > 0) {
        const turn = this._queue[0]
        this._queue.shift() // remove the first element
        return turn
    }
  })
)
.subscribe( data => {
  if (data !== undefined ) {
      this._transmitter.sendMessage(data.targetID, data.message)
  }
})

It's working properly, but is this the right way? Or anyone can tell me how best practice to use rxjs for queue.

I'm so sorry about my grammar