> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nexis.network/llms.txt
> Use this file to discover all available pages before exploring further.

# Read Data From The Nexis Native Chain Network

> Connect to Nexis Native Chain DevNet from TypeScript and read data from the blockchain!

## Summary

* **NZT** is the name of Nexis Native Chain’s native token. Each NZT is made from 1 billion
  **Lamports**.
* **Accounts** store tokens, NFTs, programs, and data. For now, we’ll focus on
  accounts that store NZT.
* **Addresses** point to accounts on the Nexis Native Chain network. Anyone can read the
  data at a given address. Most addresses are also **public keys**.

# Lesson

### Accounts

All data on Nexis Native Chain is stored in accounts. Accounts can store:

* NZT
* Other tokens, like USDC
* NFTs
* Programs, like the film review program we make in this course!
* Program data, like a film review for the program above!

### NZT

NZT is Nexis Native Chain's 'native token' - this means NZT is used to pay transaction fees,
rent for accounts, and other common. NZT is sometimes shown with the `◎` symbol.
Each NZT is made from 1 billion **Lamports**.

In the same way that finance apps typically do math in cents (for USD) and pence
(for GBP), Nexis Native Chain apps typically transfer, spend, store, and handle NZT as
Lamports, only converting to full NZT to display to users.

### Addresses

Addresses uniquely identify accounts. Addresses are often shown as base-58
encoded strings like `dDCQNnDmNbFVi8cQhKAgXhyhXeJ625tvwsunRyRc7c8`. Most
addresses on Nexis Native Chain are also **public keys**. As mentioned in the previous
chapter, whoever controls the matching secret key for an address controls the
account - for example, the person with the secret key can send tokens from the
account.

## Reading from the Nexis Native Chain Blockchain

### Installation

We use an npm package called `@nexis-network/web3.js` to do most of the work with
Nexis Native Chain. We'll also install TypeScript and `esrun`, so we can run `.ts` files on
the command line:

```bash theme={null}
npm install typescript @nexis-network/web3.js esrun
```

### Connect to the Network

Every interaction with the Nexis Native Chain network using `@nexis-network/web3.js` is going to
happen through a `Connection` object. The `Connection` object establishes a
connection with a specific Nexis Native Chain network, called a 'cluster'. For now, we'll
use the `Devnet` cluster rather than `Mainnet`. `Devnet` is designed for
developer use and testing, and `DevNet` tokens don't have real value.

```typescript theme={null}
import { Connection, clusterApiUrl } from "@nexis-network/web3.js";

const connection = new Connection(clusterApiUrl("devnet"));
console.log(`✅ Connected!`);
```

Running this TypeScript (`npx esrun example.ts`) shows:

```
✅ Connected!
```

### Read from the Network

To read the balance of an account:

```typescript theme={null}
import { Connection, PublicKey, clusterApiUrl } from "@nexis-network/web3.js";

const connection = new Connection(clusterApiUrl("devnet"));
const address = new PublicKey("CenYq6bDRB7p73EjsPEpiYN7uveyPUTdXkDkgUduboaN");
const balance = await connection.getBalance(address);

console.log(`The balance of the account at ${address} is ${balance} lamports`);
console.log(`✅ Finished!`);
```

The balance returned is in \*lamports, as discussed earlier. Web3.js provides
the constant `LAMPORTS_PER_SOL` for showing Lamports as NZT:

```typescript theme={null}
import {
  Connection,
  PublicKey,
  clusterApiUrl,
  LAMPORTS_PER_SOL,
} from "@nexis-network/web3.js";

const connection = new Connection(clusterApiUrl("devnet"));
const address = new PublicKey("CenYq6bDRB7p73EjsPEpiYN7uveyPUTdXkDkgUduboaN");
const balance = await connection.getBalance(address);
const balanceInSol = balance / LAMPORTS_PER_SOL;

console.log(`The balance of the account at ${address} is ${balanceInSol} NZT`);
console.log(`✅ Finished!`);
```

Running `npx esrun example.ts` will show something like:

```
The balance of the account at CenYq6bDRB7p73EjsPEpiYN7uveyPUTdXkDkgUduboaN is 0.00114144 NZT
✅ Finished!
```

...and just like that, we are reading data from the Nexis Native Chain blockchain!

## Lab

Let’s practice what we’ve learned, and check the balance at a particular
address.

### Load a keypair

Remember the public key from the previous chapter.

Make a new file called `check-balance.ts`, substituting your public key for
`<your public key>`.

The script loads the public key, connects to DevNet, and checks the balance:

```typescript theme={null}
import { Connection, LAMPORTS_PER_SOL, PublicKey } from "@nexis-network/web3.js";

const publicKey = new PublicKey("<your public key>");

const connection = new Connection("https://api.devnet.nexis.network", "confirmed");

const balanceInLamports = await connection.getBalance(publicKey);

const balanceInSOL = balanceInLamports / LAMPORTS_PER_SOL;

console.log(
  `💰 Finished! The balance for the wallet at address ${publicKey} is ${balanceInSOL}!`,
);
```

Save this to a file, and `npx esrun check-balance.ts`. You should see something
like:

```
💰 Finished! The balance for the wallet at address 31ZdXAvhRQyzLC2L97PC6Lnf2yWgHhQUKKYoUo9MLQF5 is 0!
```

### Get Devnet NZT

In Devnet you can get free NZT to develop with. Think of Devnet NZT like board
game money - it looks like it has value, but it doesn't have value.

[Get some Devnet NZT](https://faucet.nexis.network/) and use the public key of your
keypair as the address.

Pick any amount of NZT you like.

### Check your balance

Re-run the script. You should see your balance updated:

```
💰 Finished! The balance for the wallet at address 31ZdXAvhRQyzLC2L97PC6Lnf2yWgHhQUKKYoUo9MLQF5 is 0.5!
```

### Check other student's balances

You can modify the script to check balances on any wallet.

```typescript theme={null}
import { Connection, LAMPORTS_PER_SOL, PublicKey } from "@nexis-network/web3.js";

const suppliedPublicKey = process.argv[2];
if (!suppliedPublicKey) {
  throw new Error("Provide a public key to check the balance of!");
}

const connection = new Connection("https://api.devnet.nexis.network", "confirmed");

const publicKey = new PublicKey(suppliedPublicKey);

const balanceInLamports = await connection.getBalance(publicKey);

const balanceInSOL = balanceInLamports / LAMPORTS_PER_SOL;

console.log(
  `✅ Finished! The balance for the wallet at address ${publicKey} is ${balanceInSOL}!`,
);
```

Swap wallet addresses with your classmates in the chat and check their balances.

```bash theme={null}
% npx esrun check-balance.ts (some wallet address)
✅ Finished! The balance for the wallet at address 31ZdXAvhRQyzLC2L97PC6Lnf2yWgHhQUKKYoUo9MLQF5 is 3!
```

And check a few of your classmate's balances.

## Challenge

Modify the script as follows:

* Add instructions to handle invalid wallet addresses.
* Modify the script to connect to `mainNet` and look up some famous Nexis Native Chain
  wallets. Try `toly.sol`, `shaq.sol` or `mccann.sol`.

We'll transfer NZT in the next lesson!

<Callout type="success">
  ### Completed the lab?

  Push your code to GitHub and
  [tell us what you thought of this lesson](https://form.typeform.com/to/IPH0UGz7#answers-lesson=8bbbfd93-1cdc-4ce3-9c83-637e7aa57454)!
</Callout>