const requestIdleCallback = process.client
  ? window.requestIdleCallback || function (cb) {
    const start = Date.now()
    const idleDeadline = {
      didTimeout: false,
      timeRemaining () {
        return Math.max(0, 50 - (Date.now() - start))
      }
    }
    return window.setTimeout(function () {
      cb(idleDeadline)
    }, 1)
  }
  : (() => {}) as any as Window['requestIdleCallback']

let requestIdleCallback: Window['requestIdleCallback'] | null = null

onMounted(() => {
  if (!shouldPrefetch.value) { return }

  // add `requestIdleCallback` polyfill if not supported and need prefetch
  if (!requestIdleCallback) {
    requestIdleCallback = window.requestIdleCallback || function (cb) {
      const start = Date.now()
      const idleDeadline = {
        didTimeout: false,
        timeRemaining () {
          return Math.max(0, 50 - (Date.now() - start))
        }
      }
      return window.setTimeout(function () {
        cb(idleDeadline)
      }, 1)
    }
  }
})