How to Send a Transaction On Solana Using JavaScript

7 min read

Introduction

Hello reader! Today is an exhilarating day because we are going on an expedition to the Solana Blockchain. Solana is an up-and-coming blockchain seeking to improve upon the current ecosystem's solutions to the complex problem of providing a secure, scalable, decentralized consensus protocol. Solana has a myriad of technologies that it is employing to garner some market share from its big brother Ethereum. In this guide, you will learn how to connect to Solana, obtain funds on its devnet, and send a transaction with this new and exciting technology.

Prerequisites:

• Nodejs installed on your system.
• Familiarity with the command-line/terminal.
• A text editor to write code in.

Setting Up the Project

You need to set up your project before you start slinging Solana transactions like a penny stock day trader! To start, create a directory. We will be naming it SolanaTransaction in this guide, but feel free to name it whatever you like. After we make the new project folder, we will need a file where we write our code. Again, you can call it anything so long as it ends with the .js suffix, but we will call ours sendSol.js. Enter the following commands in your console to proceed.

mkdir SolanaTransaction
cd SolanaTransaction
touch sendSol.js

With that out of the way, crack open the sendSol.js file with your favorite text editor.

Getting a Solana Node

While this goal could be accomplished by any node connection on the Solana network, here at QuickNode, we make it quick and easy to set up a Solana node.

You can register for whatever plan best suits your needs and then make sure to launch your node under the Solana Devnet.

You can register for a free trial, as well as see pricing here

You will need the HTTPS provider for this tutorial. It should look something like this:

Connecting to Solana

To connect to the devnet that Solana offers we will need to install the @solana/web3.js library. To do so run the following command.

npm i @solana/web3.js

With the Solana's JavaScript library installed, we can now conenct to the network.

//sendSol.js
const web3 =  require("@solana/web3.js");

(async () => {
  const web3 =  require("@solana/web3.js");

  // Connect to cluster
  const connection = new web3.Connection(
    "<YOUR_QUICKNODE_URL_HERE>",
    'confirmed',
  );
  // console.log(connection) Uncomment this to test if your connection is working
})

A quick breakdown of the code:

• Line 2: importing the solana/web3.js library.
• Line 4: Calling an async lambda function that will execute all of the code when we run our script.
• line 5-8: Making a new connection object. The constructor for connection takes a string representation of an endpoint URL, and a commitment level. In our case we're calling the clusterApiUrl() function which will return the current live endpoint to the Solana Devnet.

With the connection constant configured, you will now be able to make calls to the Solana Network. If you'd like to test out if your connection is working, you can uncomment the line at the bottom to log the connection object.

Generating the Addresses and Funds

With a connection to the network, we will need to get the tools to generate the addresses and get funds for the network. We can do that with the following call. Place this bit of code below the connection, but inside the lambda function.

//sendSol.js
const from = web3.Keypair.generate();
  const airdropSignature = await connection.requestAirdrop(
    from.publicKey,
    web3.LAMPORTS_PER_SOL, // 10000000 Lamports in 1 SOL
  );
  await connection.confirmTransaction(airdropSignature);

  // Generate a new random public key
  const to = web3.Keypair.generate();

Walking through this bit of code:

• Line 2: Creating a new keypair that we will send funds from.
• Line 3-6: Requesting an airdrop for funds. Instead of going to a faucet like you would on Ethereum, Solana has this functionality baked in to its devnet. This will send 1 SOL (web3.LAMPORTS_PER_SOL) to the address (from.publicKey) that you pass in.
• Line 7: confirming the transaction using our connection's method confirmTransaction.
• Line 10: Creating a new keypair that we will send funds to.

Having done all of those previous steps, you should now have:

1. A connection to the Solana Network.
2. An account with funds to send SOL from.
3. An account address to send SOL to.

As it turns out, with all of those components you are now able to complete a transaction!

Sending the Transaction

On to the fun bit! We can now send a transaction on the network. There are two parts to this process. First, we need to create a new transaction object. Second, we have to send that transaction to another user and add our signature to it. The following block of code will show us exactly how to do that.

const transaction = new web3.Transaction().add(
    web3.SystemProgram.transfer({
      fromPubkey: from.publicKey,
      toPubkey: to.publicKey,
      lamports: web3.LAMPORTS_PER_SOL / 100,
    }),
  );

  // Sign transaction, broadcast, and confirm
  const signature = await web3.sendAndConfirmTransaction(
    connection,
    transaction,
    [from],
  );
  console.log('SIGNATURE', signature);

Creating the Transaction

Here you can see each of the previous steps has its own function. We can start with the first function web3.Transaction().add(web3.SystemProgram.transfer({})). That is quite verbose, and needs to be broken down into smaller parts to be fully understood.

1. web3.Transaction() - creates the empty Transaction object.
2. add() - Provides a method where we can add instructions to the Transaction object.
3. web3.SystemProgram.transfer() - This is the method responsible for sending the funds from one account to another. It takes several arguments. This represents lines 2-6 of our first function that we store in the transaction constant.

Parameters:

1. fromPubkey - The public key of the account that we are sending funds from.
2. toPubkey - The public key of the account that is receiving funds from the transaction.
3. lamports: - The amount of lamports to send. You can think of lamports are to Sol, what gwei are to Ether.

Signing the Transaction

With the transaction object ready to go, we now need to authorize the transaction by signing it with our secret key. The 2nd function in the code block above is responsible for this step in the process. We can break that down to get a better understanding of what is going on.

• Line 10: Declaring the signature constant, which will store the result from sendAndConfirmTransaction()
• Line 11-13: providing the arguments to the previously mentioned function. In order, the arguments are the connection object, the transaction to send, and the sender's private/public keypair represented by an array. 
• Line 15: Logging the successful signature, which is represented by a transaction hash.

With all of that done, you are now ready to run your code. I will add a final code snippet here which should be what your finished project looks like.

const web3 =  require("@solana/web3.js");

(async () => {
  // Connect to cluster
  console.log(web3.clusterApiUrl('devnet'))
  const connection = new web3.Connection(
    web3.clusterApiUrl('devnet'),
    'confirmed',
  );
  // Uncomment the below command to test your connection to your node
  //console.log(await connection.getEpochInfo())

  // Generate a new random public key
  const from = web3.Keypair.generate();
  const airdropSignature = await connection.requestAirdrop(
    from.publicKey,
    web3.LAMPORTS_PER_SOL,
  );
  await connection.confirmTransaction(airdropSignature);

  // Generate a new random public key
  const to = web3.Keypair.generate();

  // Add transfer instruction to transaction
  const transaction = new web3.Transaction().add(
    web3.SystemProgram.transfer({
      fromPubkey: from.publicKey,
      toPubkey: to.publicKey,
      lamports: web3.LAMPORTS_PER_SOL / 100,
    }),
  );

  // Sign transaction, broadcast, and confirm
  const signature = await web3.sendAndConfirmTransaction(
    connection,
    transaction,
    [from],
  );
  console.log('SIGNATURE', signature);
})();

You can now run the sendSol.js file in your terminal and get an output similar to this!

Conclusion

Congratulations! If you made it to this part you have now successfully sent a transaction on the Solana Network. Solana is a very interesting blockchain, that seemingly makes improvments upon the Ethereum Network in terms of UX. The transactions happen faster, and fees are lower. Solana has not been battle tested quite like Ethereum has, but it is certainly worth keeping an eye out on. And more importantly, you are already ahead of the curve! There aren't many that can say that they have sent a transaction on Solana using JavaScript, but you can!

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