Swapping Tokens

In the previous tutorials, we’ve learned how to create a pool, add liquidity, and remove it. Now, let’s look at one of the most common operations: swapping tokens.

Swapping tokens in a DLMM pool involves getting a quote for the desired trade and then executing the swap transaction.

Make sure you have your wallet set up. For this tutorial, I’m using a wallet loaded from the command line.

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Swap Types and Directions

Before we dive into the code, it’s important to understand the different ways you can swap tokens with Saros DLMM.

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Swap Types

There are two types of swaps available:

• Exact Input: You specify the exact amount of tokens you want to swap, and the pool will give you the corresponding amount of the other token in return.
• Exact Output: You specify the exact amount of tokens you want to receive, and the pool will calculate how much of the other token you need to provide.

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Swap Direction

Swaps can be performed in two directions:

• Swap for Y: Swap token X (base token) for token Y (quote token).
• Swap for X: Swap token Y (quote token) for token X (base token).

Now let’s see how to implement this in code.

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1. Getting a Quote

Before performing a swap, it’s a good practice to get a quote to see how many tokens you will receive. This helps you to check the price and potential slippage.

import { PYUSD_TOKEN_DEVNET, PYUSD_WSOL_POOL_DEVNET, WSOL_TOKEN_DEVNET } from "./constants.js";
import { sarosDLMM } from "./service.js";
import { PublicKey } from "@solana/web3.js";
import { loadWalletFromCLI } from "./wallet.js";

const wallet = loadWalletFromCLI();

const {amount, otherAmountOffset} = await sarosDLMM.getQuote({
    amount: BigInt(1e4),
    isExactInput: true,
    swapForY: true,
    pair: new PublicKey(PYUSD_WSOL_POOL_DEVNET.address),
    tokenBase: new PublicKey(PYUSD_TOKEN_DEVNET.mintAddress),
    tokenBaseDecimal: PYUSD_TOKEN_DEVNET.decimals,
    tokenQuote: new PublicKey(WSOL_TOKEN_DEVNET.mintAddress),
    tokenQuoteDecimal: WSOL_TOKEN_DEVNET.decimals,
    slippage: 0.5,
})

Let’s break down the parameters for getQuote:

• amount: The amount of tokens you want to swap. In this case, 1e4 lamports of the input token.
• isExactInput: We set this to true because we are using the “Exact Input” swap type. We are specifying the exact amount of tokens we want to send.
• swapForY: We set this to true to swap token X for token Y (PYUSD for WSOL in our case).
• pair, tokenBase, tokenQuote: These are the details of the pool and tokens we are interacting with.
• slippage: The percentage of price change you are willing to tolerate. Here it’s 0.5%.

The getQuote function returns the amount to be swapped and otherAmountOffset, which is the minimum amount of the other token you will receive after accounting for slippage.

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2. Executing the Swap

Once we have the quote, we can use it to execute the swap. The swap function will create the transaction for us.

const swapTx = await sarosDLMM.swap({
    amount,
    otherAmountOffset,
    pair: new PublicKey(PYUSD_WSOL_POOL_DEVNET.address),
    tokenMintX: new PublicKey(PYUSD_TOKEN_DEVNET.mintAddress),
    tokenMintY: new PublicKey(WSOL_TOKEN_DEVNET.mintAddress),
    swapForY: true,
    isExactInput: true,
    payer: wallet.publicKey,
    hook: sarosDLMM.hooksConfig,
})

Most of the parameters here are similar to getQuote. The amount and otherAmountOffset are taken directly from the response of the getQuote call.

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3. Sending the Transaction

Now that we have the swap transaction, we just need to sign it and send it to the Solana network.

const {blockhash} = await sarosDLMM.connection.getLatestBlockhash({ commitment: "confirmed" });

swapTx.recentBlockhash = blockhash;
swapTx.feePayer = wallet.publicKey;
swapTx.sign(wallet);

const signature = await sarosDLMM.connection.sendRawTransaction(swapTx.serialize(), {
    skipPreflight: false,
    preflightCommitment: "confirmed",
})

console.log("Transaction signature:", signature);

And that’s it! After the transaction is confirmed, the token swap is complete.