A React Hook to determine if a tab of your application is the "leader" using BroadcastChannel and leader election

useBroadcastLeader.ts

import { BroadcastChannel, createLeaderElection } from 'broadcast-channel'
import React from 'react'

const channels = {}

export function useBroadcastLeader(id = 'default') {
  const [isBroadcastLeader, setIsBroadcastLeader] = React.useState(false)

  React.useEffect(() => {
    if (!channels[id]) {
      const channel = new BroadcastChannel('useBroadcastLeader_' + id)
      const elector = createLeaderElection(channel)

      channels[id] = {
        channel,
        elector,
        subscribers: [],
      }

      elector.awaitLeadership().then(() => {
        channels[id].subscribers.forEach(sub => {
          sub(true)
        })
      })
    }

    channels[id].subscribers.push(setIsBroadcastLeader)

    return () => {
      channels[id].subscribers = channels[id].subscribers.filter(
        d => d !== setIsBroadcastLeader
      )

      if (!channels[id].subscribers.length) {
        channels[id].elector.die()
        channels[id].channel.close()

        delete channels[id]
      }
    }
  }, [id])

  const waitForBroadcastLeader = React.useCallback(
    () => channels[id].awaitLeadership(),
    [id]
  )

  return {
    isBroadcastLeader,
    waitForBroadcastLeader,
  }
}

Thank you

@tannerlinsley should line 44 be something more like the following?

-    () => channels[id].awaitLeadership(),
+    () => channels[id].elector.awaitLeadership(),