web_app/src/hooks/useAsyncMemo.tsx

import { DependencyList, useEffect, useState } from 'react'

export function useAsyncMemo<T>(
  factory: () => Promise<T> | undefined | null,
  deps: DependencyList
): T | undefined
export function useAsyncMemo<T>(
  factory: () => Promise<T> | undefined | null,
  deps: DependencyList,
  initial: T
): T
export function useAsyncMemo<T>(
  factory: () => Promise<T> | undefined | null,
  deps: DependencyList,
  initial?: T
) {
  const [val, setVal] = useState<T | undefined>(initial)

  useEffect(() => {
    let cancel = false
    const promise = factory()
    if (promise === undefined || promise === null) return
    promise.then(v => {
      if (!cancel) {
        setVal(v)
      }
    })
    return () => {
      cancel = true
    }
  }, deps)
  return val
}