Using Custom Contracts

/**
* Run:
* npm install ethers dotenv
*/

import { Contract, JsonRpcProvider, Wallet } from "ethers";
import dotenv from "dotenv";
dotenv.config();

const SEND_NUMBER_ADDR = "0xd2AAa00100000000000000000000000000000000";
const SEND_NUMBER_ABI = [
	"function sendNumber(uint256 number) external",
	"function lastNumber() external view returns (uint256)"
];

const sChainAProvider = new JsonRpcProvider(process.env.RPC_URL);
const sChainBProvider = new JsonRpcProvider(process.env.PRC_URL);

const wallet = new Wallet(process.env.PRIVATE_KEY, sChainAProvider);
const contractA = new Contract(SEND_NUMBER_ADDR_A, SEND_NUMBER_ABI, wallet);
const contractB = new Contract(SEND_NUMBER_ADDR_B, SEND_NUMBER_ABI, sChainBProvider);	
const txA = await contractA.sendNumber(BigInt(5));
await txA.ok();

// The following can be replaced with "listening for an event", however,
// a while loop is more intuitive for a new developer
while (true) {
	const lastNumber = await contractB.lastNumber();
	if (lastNumber === BigInt(5)) {
		console.log("Posted!");
		break;
	}
	await new Promise(res => setTimeout(res, 2000)); // Sleep 2 seconds
}