Set up your project

Install dependencies

First things first, set up a new TypeScript project with a src/index.ts file and install the @solana/kit library. Additionally, to keep this tutorial focused on the Kit library, we'll use tsx to compile and run our TypeScript code.

npm install @solana/kit tsx

Add some scripts

Let's also create a start script that runs tsx src/index.ts and a validator script to start a local Solana validator. Your package.json should look something like this:

{
  "name": "kit-tutorial",
  "version": "1.0.0",
  "scripts": {
    "start": "tsx src/index.ts",
    "validator": "solana-test-validator"
  },
  "dependencies": {
    "@solana/kit": "^2.1.0",
    "tsx": "^4.19.3"
  }
}

From now on, we just need to make sure a Solana validator is running using the validator script before we can run our start script.

Create a client object

To simplify our development, we'll create a small Client type specific to our application. Meaning it will include all the necessary objects and functions we need to interact with Solana.

The first two things we need are the RPC and RPC Subscriptions objects which allow us to send requests to the network and listen for network events respectively. We'll need both of them to fetch accounts and send transactions.

Let's create a new src/client.ts file and add the following Client type:

import { Rpc, RpcSubscriptions, SolanaRpcApi, SolanaRpcSubscriptionsApi } from "@solana/kit";
 
export type Client = {
  rpc: Rpc<SolanaRpcApi>;
  rpcSubscriptions: RpcSubscriptions<SolanaRpcSubscriptionsApi>;
};

Then, let's create a helper function to create a new cached Client object that we can use throughout our application:

import { createSolanaRpc, createSolanaRpcSubscriptions } from "@solana/kit";
 
let client: Client | undefined;
export function createClient(): Client {
  if (!client) {
    client = {
      rpc: createSolanaRpc("http://127.0.0.1:8899"),
      rpcSubscriptions: createSolanaRpcSubscriptions("ws://127.0.0.1:8900"),
    };
  }
  return client;
}

We'll add more to this Client type as we progress through the tutorial but for now, this is all we need to get started.

Run the tutorial

Finally, let's go back to our src/index.ts file and add an asynchronous tutorial function that we will run immediately to start our tutorial. For now, let's just use our Client object to fetch the balance of a specific account.

We can do this by creating an Address type via the address helper and fetching the balance via the getBalance method of the rpc object.

import { address } from "@solana/kit";
import { createClient } from "./client";
 
// Run the tutorial.
tutorial();
 
async function tutorial() {
  const client = createClient();
  const account = address("TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb");
  const { value: balance } = await client.rpc.getBalance(account).send();
  console.log(`Balance: ${balance} lamports.`);
}

You should now see something like this when you run the start script:

Balance: 1141440 lamports.

In the next article, we'll learn how to generate a wallet that can spend lamports and sign transactions.