Building with Native API

// Initialize the API as in previous sections
...

// Retrieve the chain name
const chain = await api.rpc.system.chain();

// Retrieve the latest header
const lastHeader = await api.rpc.chain.getHeader();

// Log the information
console.log(`${chain}: last block #${lastHeader.number} has hash ${lastHeader.hash}`);

...
let count = 0;

// Subscribe to the new headers
const unsubscribe = await api.rpc.chain.subscribeNewHeads((lastHeader) => {
  console.log(`${chain}: last block #${lastHeader.number} has hash ${lastHeader.hash}`);

  if (++count === 10) {
    unsubscribe();
  }
});

// Initialize the API as in previous sections
...

// The actual address that we will use
const ADDR = '0xE04CC55ebEE1cBCE552f250e85c57B70B2E2625b';

const [now, { nonce, data: balance }] = await Promise.all([
  api.query.timestamp.now(),
  api.query.system.account(ADDR)
]);

console.log(`${now}: balance of ${balance.free} and a nonce of ${nonce}`);

...

// Retrieve the current timestamp via subscription
const unsubscribe = await api.query.timestamp.now((moment) => {
  console.log(`The last block has a timestamp of ${moment}`);

  // unsubscribe(); call to stop receiving updates
});

import { Keyring } from "@polkadot/keyring";
import { stringToU8a, u8aToHex, hexToU8a } from "@polkadot/util";

// create a keyring with some non-default values specified
const keyring = new Keyring({ type: "ethereum" });
const seedU8a = hexToU8a(ALICE_PRIVATE_KEY);
const alice = keyring.addFromSeed(seedU8a);

...
// Sign and send a transfer from Alice to Bob
const txHash = await api.tx.balances
  .transfer(BOB, 12345)
  .signAndSend(alice);

// Show the hash
console.log(`Submitted with hash ${txHash}`);

...
// Make a transfer from Alice to Bob, waiting for inclusion
const unsubscribe = await api.tx.balances
  .transfer(BOB, 12345)
  .signAndSend(alice, (result) => {
    console.log(`Current status is ${result.status.type}`);

    if (result.status.isInBlock) {
      console.log(`Transaction included at blockHash ${result.status.asInBlock}`);
    } else if (result.status.isFinalized) {
      console.log(`Transaction finalized at blockHash ${result.status.asFinalized}`);
      unsubscribe();
    }
  });

...
// Make a transfer from Alice to BOB, waiting for inclusion
const unsubscribe = await api.tx.balances
  .transfer(BOB, 12345)
  .signAndSend(alice, ({ events = [], status, txHash }) => {
    console.log(`Current status is ${status.type}`);

    if (status.isFinalized) {
      console.log(`Transaction included at blockHash ${status.asFinalized}`);
      console.log(`Transaction hash ${txHash.toHex()}`);

      // Loop through Vec<EventRecord> to display all events
      events.forEach(({ phase, event: { data, method, section } }) => {
        console.log(`\t' ${phase}: ${section}.${method}:: ${data}`);
      });

      unsubscribe();
    }
  });

// construct a transaction
const transfer = api.tx.balances.transfer(BOB, 12345);

// retrieve the payment info
const { partialFee, weight } = await transfer.paymentInfo(alice);

console.log(`transaction will have a weight of ${weight}, with ${partialFee.toHuman()} weight fees`);

// send the tx
transfer.signAndSend(alice, ({ events = [], status }) => { ... });