Exploring Your Blockchain Connection!

Great! You’ve successfully connected to the Nimiq network and established consensus. Now let’s explore what information we can get from the network.

What You Can Access

Once consensus is established, your client has access to the current state of the blockchain. You’re now connected to a global network of computers all maintaining the same digital ledger!

Network Information

Let’s confirm which Nimiq network you’re connected to:

const networkId = await client.getNetworkId()
let networkName = 'unkwown'
if (networkId === 5)
  networkName = 'testnet'
else if (networkId === 6)
  networkName = 'mainnet'
console.log(`🌐 Connected to ${networkName} network`)

This tells you exactly which version of Nimiq you’re talking to - the testnet (for learning) or the main network.

Head Block Information

The head block is the latest block in the blockchain - think of it as the “latest news” from the network. Add this code to see current blockchain data:

// Get the latest block information
const headBlock = await client.getHeadBlock()
console.log(`🏔️  Block Height: ${headBlock.height}`)
console.log(`🧱 Block Hash: ${headBlock.hash}`)
console.log(`⏰ Block Time: ${new Date(headBlock.timestamp * 1000).toLocaleString()}`)

What you’re seeing:

• Block Height: How many blocks exist in the chain (like page numbers in a book)
• Block Hash: A unique fingerprint that identifies this specific block
• Block Time: When this block was created and added to the blockchain

Listening for New Blocks

Instead of asking for the latest block repeatedly, you can subscribe to get notified every time a new block is added to the chain. It’s like getting a push notification for blockchain updates!

// Subscribe to new head blocks
await client.addHeadChangedListener((hash) => {
  console.log(`🎉 New block mined! Hash: ${hash}`)
})

Now, your application will react in real-time as the blockchain grows. This is incredibly powerful for building dynamic and responsive dapps.

Getting Full Block Details on Subscription

But what if you need more than just the hash? You can combine what you’ve learned to get the full block data in real-time.

Inside your listener, you can use the getBlock() method with the new hash to fetch the complete block details:

// Subscribe to new head blocks and get the full block
const listenerId = await client.addHeadChangedListener(async (hash) => {
  const block = await client.getBlock(hash)
  console.log(`🎉 New block. Block number: ${block.height}. Hash: ${hash}`)
})

console.log('👂 Subscribed to head changes and now getting full blocks!')

What This Means

With these simple API calls, you’re accessing live data from a global blockchain network:

• Global Consensus: The block data you see is agreed upon by nodes worldwide
• Real-Time Updates: This information updates as new blocks are created
• Decentralized Access: You’re reading directly from the blockchain, no middleman needed