@polkadot-api/json-rpc-provider-proxy

This package exports getSyncProvider, a function to create JsonRpcProviders that will act as if the connection happen synchronously.

1export type AsyncJsonRpcProvider = (
2  onMessage: (message: string) => void,
3  onHalt: () => void,
4) => JsonRpcConnection
5
6function getSyncProvider(
7  input: () => Promise<AsyncJsonRpcProvider>,
8): JsonRpcProvider

The returned provider will buffer up every message until it can get the JsonRpcConnection, at which point it will send every message buffered.