README.md

rescript-use-sync-external-store

This is a zero-cost ReScript binding to use-sync-external-store. Specifically to use-sync-external-store/shim.

Usage

See __test__/SyncExternalStore_test.res for usage.

Migration from use-subscription

If you were using rescript-use-subscription before, migration should be fairly straightforward:

Before

let {useSubscription} = module(UseSubscription)

@react.component
let make = () => {
  let options = React.useMemo(() => {
    UseSubscription.getCurrentValue: () => Some(1),
    subscribe: callback => {
      callback(. Some(1))

      (.) => ()
    },
  })
  let val = useSubscription(options)

  <div>{val->Belt.Option.mapWithDefault(React.null, React.int)}</div>
}

After

let val = ref(Some(1))

@react.component
let make = () => {
  let val = SyncExternalStore.use(
    ~getSnapshot=() => val.contents,
    ~subscribe=callback => {
      callback()
      () => ()
    },
    (),
  )

  <div> {val->Belt.Option.mapWithDefault(React.null, React.int)} </div>
}