How to get chainId / network name / network id etc in hardhat?

Question

I'm looking to get the ID of the chain/network I'm running a script on in hardhat. How can I get the names and IDs?

Answer 1

There are a few ways to get the network/chain name/id. We are going to assume you are in a script that you'd like to run, or a test. When running these, you must have a hardhat.config.ts or hardhat.config.js, and you must be running the script "in" hardhat. For example: npx hardhat run scripts/your_script_here.ts

import hre from 'hardhat'
const networkName = hre.network.name
const chainId = hre.network.config.chainId

This means, you'll need a hardhat.config that looks something like:

const config: HardhatUserConfig = {
    defaultNetwork: 'hardhat',
    networks: {
        hardhat: {
            chainId: 31337,
            accounts: [process.env.PRIVATE_KEY!],
        },

You could also create a file that has a mapping between your network/chain name and ID.

Alternatively, you could use hardhat-deploy with something like:

import { HardhatRuntimeEnvironment } from 'hardhat/types'
import { DeployFunction } from 'hardhat-deploy/types'
const deployScript: DeployFunction = async function (
  hre: HardhatRuntimeEnvironment
) {
  const { getChainId } = hre
  const chainId = await getChainId()

Combined with a network mapping.

Answer 2

Another way to do it that works for me is

const { ethers } = require("hardhat");
const network = await ethers.getDefaultProvider().getNetwork();
console.log("Network name=", network.name);
console.log("Network chain id=", network.chainId);

As with the accepted answer, you must be running "in" Hardhat for this to work.

Answer 3

Add your network to networks section in hardhat config file:

networks: {
    hardhat: {},
    polygon: {
      url: JSON_RPC_URL, // Alchemy/Infura/QuickNode,...
      chainId: 137, // optional,
      accounts: [YOUR_ACCOUNT_PRIVATE_KEY] // optional
    }
}

then in your scripts to get chainId as hex string:

import { network } from 'hardhat';
const chainIdHex = await network.provider.send('eth_chainId');