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Ethers.js

ethers.js is a powerful JavaScript library for interacting with Ethereum and other EVM-compatible blockchain networks.

In this guide, we'll walk you through how to use ethers.js to interact with smart contracts on the Flow Blockchain.

Installation​

To begin using ethers.js in your project, you'll need to install the package. You can do this by running the following command:


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bashCopy code
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npm install --save ethers

Setup​

After installing ethers.js, the next step is to import it into your project.

You can do this by adding the following line of code at the beginning of your JavaScript file:


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const ethers = require('ethers');

Connecting to Flow​

To connect to the Flow Blockchain using ethers.js, you need to create a new JsonRpcProvider instance with the appropriate RPC URL for Flow:


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const ethers = require('ethers');
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const url = 'https://testnet.evm.nodes.onflow.org/';
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const provider = new ethers.providers.JsonRpcProvider(url);

Note: If you want to connect to the Flow testnet, replace the above URL with https://mainnet.evm.nodes.onflow.org.

Reading Data from the Blockchain​

Once your provider is set up, you can start reading data from the Flow Blockchain. For instance, to retrieve the latest block number, you can use the getBlockNumber method:


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async function getLatestBlock() {
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const latestBlock = await provider.getBlockNumber();
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console.log(latestBlock);
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}

Writing Data to the Blockchain​

To send transactions or write data to the Flow Blockchain, you need to create a Signer. This can be done by initializing a new Wallet object with your private key and the previously created Provider:


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const privateKey = 'YOUR_PRIVATE_KEY';
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const signer = new ethers.Wallet(privateKey, provider);

Note: Replace 'YOUR_PRIVATE_KEY' with the actual private key of the wallet you want to use.

Interacting with Smart Contracts​

ethers.js also enables interaction with smart contracts on the Flow Blockchain. To do this, create a Contract object using the ABI (Application Binary Interface) and the address of the deployed contract:


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const abi = [
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// ABI of deployed contract
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];
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const contractAddress = 'CONTRACT_ADDRESS';
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// read-only contract instance
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const contract = new ethers.Contract(contractAddress, abi, provider);

For contracts that require writing, you'll need to provide a Signer object instead of a Provider:


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// write-enabled contract instance
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const contract = new ethers.Contract(contractAddress, abi, signer);

Note: Replace 'CONTRACT_ADDRESS' with the actual address of your deployed contract.

After setting up your Contract object, you can call methods on the smart contract as needed:


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async function setValue(value) {
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const tx = await contract.set(value);
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console.log(tx.hash);
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}
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async function getValue() {
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const value = await contract.get();
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console.log(value.toString());
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}