Fetching Cryptocurrency Prices With Uniswap V3 And Ethers Js V5

Fetching Cryptocurrency Prices with Uniswap V3 and Ethers.js V5

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](https://blog.blockmagnates.com/?source=post_page---byline--2fb0b3ddd33b--------------------------------)·2 min read·Jan 31, 2024

In the ever-evolving world of cryptocurrencies, accessing real-time exchange rates can be a crucial requirement for various applications. This article delves into how one can utilize Uniswap V3 and Ethers.js V5, a prominent Ethereum library, to fetch the current exchange rate between two cryptocurrencies.

Setting Up the Environment

To begin, ensure that Node.js is installed on your system. We will be using Ethers.js V5, a library that allows interaction with the Ethereum blockchain.

Dependencies:

- `ethers`: A library for interacting with the Ethereum Blockchain and its ecosystem.

- `@uniswap/v3-periphery`: Provides ABI for interacting with Uniswap V3.

Environment Variables:

- `ETHEREUM_MAINNET_RPC`: The RPC URL for Ethereum’s Mainnet.

- `WALLET_PRIVATE_KEY`: Your Ethereum wallet private key.

The Code Explained

Importing Libraries and Setting Up

Firstly, we import the necessary libraries and set up the environment.

const { ethers } = require(“ethers”);

const { abi: QuoterABI } = require(“@uniswap/v3-periphery/artifacts/contracts/lens/Quoter.sol/Quoter.json”);

require(‘dotenv’).config();

const provider = new ethers.providers.JsonRpcProvider(process.env.ETHEREUM\_MAINNET\_RPC);

Establishing Contract and Provider

We establish a connection to the Ethereum mainnet via the provider and set up the Uniswap V3 quoter contract.

const quoterAddress = “0xb27308f9F90D607463bb33eA1BeBb41C27CE5AB6”;

const signer = new ethers.Wallet(process.env.WALLET\_PRIVATE\_KEY, provider);

const quoterContract = new ethers.Contract(quoterAddress, QuoterABI, provider);

Fetching Prices Function

`fetchPrice` function takes in the addresses of the two tokens and the amount to be converted. It then interacts with the Uniswap V3 quoter contract to fetch the conversion rate.

const fetchPrice = async (addressFrom, addressTo, humanValue) => {

const amountIn = ethers.utils.parseUnits(humanValue.toString(), 18);

const quotedAmountOut = await quoterContract.callStatic.quoteExactInputSingle(

addressFrom, addressTo, 3000, amountIn, 0);

return ethers.utils.formatUnits(quotedAmountOut.toString(), 18);

};

Main Function

In the `main` function, we define the token addresses (here, WETH and DAI) and call `fetchPrice`.

const main = async () => {

const addressFrom = “0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2”; // WETH

const addressTo = “0x6B175474E89094C44Da98b954EedeAC495271d0F”; // DAI

const humanValue = “1”; // 1 ETH

const result = await fetchPrice(addressFrom, addressTo, humanValue);

console.log(\`The price of ${humanValue} ${addressFrom} in ${addressTo} is ${result}\`);

};

main();

Conclusion

This script provides a straightforward approach to obtaining the exchange rates between two cryptocurrencies using Uniswap V3 and Ethers.js. It’s a valuable tool for developers working on financial applications where real-time data is critical.

Remember to handle your private keys securely and never expose them in your codebase. Happy coding!