Interview

Project Goal Summary

Your goal is to write code to subscribe (and unsubscribe) to real-time solana token wallet balances and display the data. This balance data for a certain token may be displayed in more than one component at the same time.

Libraries needed:

• @solana/web3.js
• @solana/spl-token

Wallet address to use:

5QRZKZ65CuQPu3XwKaNnK9L2ASuzvrz4NGpAUrWEDoQm

Token addresses to listen to:

• BONK: DezXAZ8z7PnrnRJjz3wXBoRgixCa6xjnB7YaB1pPB263
  • Decimals: 5
• WIF: 21AErpiB8uSb94oQKRcwuHqyHF93njAxBSbdUrpupump
  • Decimals: 6

Connect to RPC:

import { Connection, PublicKey } from '@solana/web3.js';
const RPC_URL = 'https://gene-v4mswe-fast-mainnet.helius-rpc.com';
const SOLANA_CONNECTION = new Connection(RPC_URL);

const LAMPORT_PER_SOL = 1000000000;

Get SOL balance:

const walletPublicKey = new PublicKey(WALLET_ADDRESS);
SOLANA_CONNECTION.onAccountChange(
  walletPublicKey,
  (info) => {
    console.log('SOL in lamports', info.lamports);
  },
  { commitment: 'processed' }
);

Get SPL Token Balance:

Function to get associated token address:

import { getAssociatedTokenAddress } from '@solana/spl-token';

// get associated token address

SOLANA_CONNECTION.onAccountChange(
  ASSOCIATED_TOKEN_ADDRESS,
  (info) => {
    const d = info.data;
    if (d.length === 165 || d.length === 182) {
      const low = d.readUInt32LE(64);
      const high = d.readUInt32LE(68);
      const raw = high * 2 ** 32 + low;
      const divisor = 10 ** DECIMALS_HERE;
      const balance = raw / divisor;
    }
  },
  { commitment: 'processed' }
);