SuspenseFetch.js

const Unitialized = -1;
const Pending = 0;
const Resolved = 1;
const Rejected = 2;

function suspenseFetch(url) {
  const payload = {
    _status: Unitialized,
    _result: () => fetch(url)
  }

  return () => {
    if (payload._status === Uninitialized) {
      const promise = payload._result()
      payload._status = Pending
      payload._result = promise

      promise.then((res) => {
        if (payload._status === Pending) {
          payload._status = Resolved
          payload._result = res
        }
      }, (err) => {
        if (payload._status === Pending) {
          payload._status = Rejected
          payload._result = err
        }
      })
    } else if (payload._status === Resolved) {
      return payload._result
    } else {
      throw payload._result
    }
  }
}

// in app
const fetchUser = suspenseFetch(`/users/1`)

const User = () => {
  const user = fetchUser()

  return <div>{user.name}</div>
}

const App = () => (
  <Suspense fallback={<h1>Loading user...</h1>}>
    <User>
  </Suspense>
)