author_submitAndWatchExtrinsic - Moonbeam RPC Method

import { ApiPromise, WsProvider, Keyring } from '@polkadot/api';

async function sendAndConfirm(api, sender, tx, timeoutMs = 120000) {
  return new Promise((resolve, reject) => {
    const timer = setTimeout(() => {
      reject(new Error('Transaction confirmation timed out'));
    }, timeoutMs);

    tx.signAndSend(sender, ({ status, dispatchError, events }) => {
      if (dispatchError) {
        clearTimeout(timer);
        if (dispatchError.isModule) {
          const { docs, name, section } = api.registry.findMetaError(dispatchError.asModule);
          reject(new Error(`${section}.${name}: ${docs.join(' ')}`));
        } else {
          reject(new Error(dispatchError.toString()));
        }
      }

      if (status.isFinalized) {
        clearTimeout(timer);
        resolve({
          blockHash: status.asFinalized.toHex(),
          events: events.map((e) => `${e.event.section}.${e.event.method}`)
        });
      }
    }).catch((err) => {
      clearTimeout(timer);
      reject(err);
    });
  });
}

async function submitBatch(api, sender, calls) {
  const results = [];
  let nonce = (await api.rpc.system.accountNextIndex(sender.address)).toNumber();

  for (const call of calls) {
    const result = await new Promise((resolve, reject) => {
      call.signAndSend(sender, { nonce: nonce++ }, ({ status, dispatchError }) => {
        if (dispatchError) {
          const decoded = dispatchError.isModule
            ? api.registry.findMetaError(dispatchError.asModule)
            : { name: dispatchError.toString() };
          reject(new Error(`Dispatch error: ${decoded.name}`));
        }

        if (status.isFinalized) {
          resolve({ blockHash: status.asFinalized.toHex(), nonce: nonce - 1 });
        }
      });
    });
    results.push(result);
    console.log(`Tx nonce=${result.nonce} finalized in ${result.blockHash}`);
  }

  return results;
}

async function sendWithReorgHandling(api, sender, tx) {
  let includedBlock = null;

  return new Promise((resolve, reject) => {
    tx.signAndSend(sender, ({ status, events }) => {
      if (status.isReady) {
        console.log('Transaction in ready queue');
      }

      if (status.isInBlock) {
        includedBlock = status.asInBlock.toHex();
        console.log(`Included in block: ${includedBlock}`);
      }

      if (status.isRetracted) {
        console.warn(`Block retracted: ${status.asRetracted.toHex()} -- waiting for re-inclusion`);
        includedBlock = null;
      }

      if (status.isFinalized) {
        console.log(`Finalized in block: ${status.asFinalized.toHex()}`);
        resolve({ finalized: status.asFinalized.toHex(), events });
      }

      if (status.isDropped || status.isInvalid) {
        reject(new Error(`Transaction ${status.type}`));
      }

      if (status.isUsurped) {
        reject(new Error(`Transaction usurped by ${status.asUsurped.toHex()}`));
      }
    });
  });
}