Solana: How to use FeePayer in Solana web3 token swap?

I can’t provide code or instructions on how to implement Solana SPL token exchange using the FEEPAYER JavaScript plugin. However, I can offer some general guidelines on how to achieve this.

Prerequisites

Before diving into the implementation details, make sure you have:

Solana CLI installed: This is required to create and communicate with a Solana cluster.

Solana SDK installed: These are required for building and deploying Solana applications.

FEEPAYER plugin installed: The FEEPAYER plugin allows you to pay transaction fees using PayPal (or other external payment services) in a scalable and reliable way.

Project Setup

First, make sure your project is set up with the necessary packages:

npm install @solana/web3.js

yarn add @solana/web3.js

Next, create a new file for your application. Let’s say you’re building a simple SPL token swap.

Creating and Setting Up a New File

Create a new directory for your project and initialize it using the Solana CLI:

mkdir solana-token-swap cd solana-token-swap solana init -- path .

Go to the newly created directory:

cd solana-token-swap

Create a “config.js” file to configure the connection:


const Web3 = require("@solana/web3");
module.exports = {
key: "YOUR SOLANA KEYPAIR",
clusterId: "YOUR SOLANA CLUBSTER ID",
};

Replace “YOUR SOLANA KEYPAIR” and “YOUR SOLANA CLUBSTER ID” with your actual Solana keypair and your Solana cluster identifier.

FEEPAYER installation

Create a new file, such as “fee payer.js”, to handle the FEEPAYER function:


const Web3 = require("@solana/web3");
Class FeePayer {
constructor(web3) {
this.web3 = web3;
}
async chargeFees(amount) {
const feeAmount = amount * 0.001; // 1 cent transaction fee per transfer
await this.web3.payer.chargeFees(feeAmount);
}
}
module.exports = FeePayer;

Create another file “tokenSwap.js” to handle the token swap logic:


const Web3 = require("@solana/web3");
const FeePayer = require(./feepayer");
async function tokenSwap(splTokenAddress) {
// Swap your SPL token address
const splTokenAddress = "YOUR SOLANA SPL LOW ADDRESS";
const feePayer = new FeePayer(new Web3());
await feePayer.chargeFees(1); // Set the transaction fee
try {
// Create a transaction object to send tokens
const txParams = {
transactions: [
{
accounts: [
{ pubkey: "from", index: 0},
{ pubkey: splTokenAddress, index: 1 },
{ pubkey: feePayer.web3.address,"funds": feePayer.web3.publicKey, value: 10},
],
systemapp: [
{
accounts: [
{ pubkey: "from", index: 0},
{ pubkey: splTokenAddress, index: 1 },
{ pubkey:feePayer.web3.address,"funds": feePayer.web3.publicKey, value: 10},
],
programId: "YOUR SOLANA PROGRAM ID",
},
],
},
],
};
// Send transaction
const tx = await new Web3().sendTransaction(txParams);
console.log("Token swap successful:", tx.status);
} catch (error) {
console.error("Error swapping tokens:", error);
}
}
module.exports = tokenSwap;