ethers.js

ethers.js is a JavaScript library that allows developers to interact with EVM-compatible blockchain networks.

You can use ethers.js to interact with smart contracts deployed on the Telos network.

Installing ethers.js

If using NPM, you must first install ethers.

npm install --save ethers

Setup

Before you can start using ethers.js, you need to import it into your project.

You can choose to import all of ethers, or just select specific items.

// Import everything
import { ethers } from "ethers";

// Import just a few select items
import { BrowserProvider, parseUnits } from "ethers";

// Import from a specific export
import { HDNodeWallet } from "ethers/wallet";

Connecting to Telos

You can connect to Telos by instantiating a new ethers.js JsonRpcProvider object with a RPC URL of the Telos network.

// for Telos Testnet, use https://testnet.telos.net
const url = 'https://mainnet.telos.net'
provider = new ethers.JsonRpcProvider(url)

Interacting With Telos

Querying State

Now that we have our provider set up from the previous step, we can query the blockchain!

// Look up the current block number (i.e. height)
await provider.getBlockNumber()
// 338037822

// Get the current balance of an account
balance = await provider.getBalance("ethers.eth")
// 4085267032476673080n

// Since the balance is in wei, you may wish to display it
// in ether instead.
formatEther(balance)
// '10.08526703247667308'

// Get the next nonce required to send a transaction
await provider.getTransactionCount("ethers.eth")
// 2

Sending Transactions

To send a transaction in this example, we use a signer like MetaMask. Because the usrs private keys are not accessible directly to your code, we instead make the requests via a Signer.

// When sending a transaction, the value is in wei, so parseEther
// converts ether to wei.
tx = await signer.sendTransaction({
  to: "ethers.eth",
  value: parseEther("1.0")
});

// Often you may wish to wait until the transaction is mined
receipt = await tx.wait();

Interacting With a Smart Contract

You can use ethers.js to interact with a smart contract on Telos by instantiating a Contract object using the ABI and address of a deployed contract:

abi = [
  // ABI of deployed contract
]

// Create a contract object that is read only
contract = new Contract("CONTRACT_ADDRESS", abi, provider)

To include functions that will change state on the blockchain, just swap the provider for the signer when creating the contract object.

// Create a contract object that can change state
contract = new Contract("CONTRACT_ADDRESS", abi, signer)

Now you can read and write data on the Telos blockchain! The example below assumes a contract like an ERC20 and sends a transaction!

// Send 1 Token
amount = parseUnits("1.0", 18);

// Send the transaction
tx = await contract.transfer("ethers.eth", amount)

// ...wait for the transaction to be included.
await tx.wait()