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Hardhat

Hardhat is a development environment for Ethereum based software.

Hardhat allows developers to test, compile, debug and distribute their dapps on the Ethereum blockchain It has stack tracking and the ability to log errors and messages to the console, making it easier for developers to analyze and troubleshoot the causes of errors.

Hardhat also offers a variety of utility plug-ins which can be installed to make development easier.

Hardhat Features​

  • Hardhat provides well-organized documents and tutorial documents for developers new to Hardhat.

  • Hardhat provides a wide range of libraries and plug-ins, and allows users to create plug-ins themselves.

  • Hardhat provides a flexible test environment for developers by providing a Hardhat network, a local test environment that can directly interact with smart contracts.

Install Hardhat​

To install Hardhat create an empty folder and initialize a npm project (i.e. npm init).

npm init

npm install --save-dev hardhat

Once it's installed, just run this command and follow its instructions:

npx hardhat

Hardhat Configuration​

If you run npx hardhat now, you will be shown some options to facilitate project creation.

You can create a js/ts-based project or create a blank hardhat.config.js file using the following options:

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👷 Welcome to Hardhat v2.12.0 👷‍

? What do you want to do? … 
❯ Create a JavaScript project
  Create a TypeScript project
  Create an empty hardhat.config.js
  Quit

If you select Create a JavaScript project, you can use the following process to create a project.

👷 Welcome to Hardhat v2.12.0 👷‍

✔ What do you want to do? · Create a JavaScript project
? Hardhat project root: › /Users/XXXX
? Do you want to add a .gitignore? (Y/n) › 
? Help us improve Hardhat with anonymous crash reports & basic usage data? (Y/n) ›

If the project is successfully created, the following message is printed.

✨ Project created ✨

See the README.md file for some example tasks you can run

Give Hardhat a star on Github if you're enjoying it! 💞✨

     https://github.com/NomicFoundation/hardhat

The structure of the created project is as follows:

contracts/
scripts/
test/
hardhat.config.js
README.md
  • contracts/ is where the source files for your contracts should be.
  • test/ is where your tests should go.
  • scripts/ is where simple automation scripts go.

If you select Create a TypeScript project, you can use the following process to create a project.

👷 Welcome to Hardhat v2.12.0 👷‍

✔ What do you want to do? · Create a TypeScript project
✔ Hardhat project root: · /Users/XXX
✔ Do you want to add a .gitignore? (Y/n) ·

If the project is successfully created, the following message is printed.

✨ Project created ✨

See the README.md file for some example tasks you can run

Give Hardhat a star on Github if you're enjoying it! 💞✨

     https://github.com/NomicFoundation/hardhat

The structure of the created project is as follows:

contracts/
scripts/
test/
hardhat.config.js
README.md
tsconfig.json
  • contracts/ is where the source files for your contracts should be.
  • test/ is where your tests should go.
  • scripts/ is where simple automation scripts go.

If you select Create an empty hardhat.config.js, Hardhat will create a hardhat.config.js like the following:

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: "0.8.17",
};

Compiling smart contracts​

To compile your contracts in your Hardhat project, use the built-in compile task:

$ npx hardhat compile
// Download the compiler at the first compile run of the project.
Downloading compiler 0.8.17
Compiling...
Compiled 1 contract successfully

The compiled artifacts will be saved in the artifacts/ directory by default. If the artifacts directory does not exist, it is automatically created, and you can modify the structure.

The compile command has the following options:

Usage: hardhat [GLOBAL OPTIONS] compile [--concurrency <INT>] [--force] [--no-typechain] [--quiet]

OPTIONS:

  --concurrency 	Number of compilation jobs executed in parallel. Defaults to the number of CPU cores - 1 (default: 7)
  --force       	Force compilation ignoring cache 
  --no-typechain	Skip Typechain compilation 
  --quiet       	Makes the compilation process less verbose 

compile: Compiles the entire project, building all artifacts

Testing smart contracts​

For smart contract testing, it is recommended that you proceed with the test while writing an example code by referring to the Testing contracts page.

Deploying smart contracts​

You can use the following steps to deploy smart contracts from localhost.

  1. Start a local node
npx hardhat node

The node command has the following options:

Usage: hardhat [GLOBAL OPTIONS] node [--fork <STRING>] [--fork-block-number <INT>] [--hostname <STRING>] [--port <INT>]

OPTIONS:

  --fork             	The URL of the JSON-RPC server to fork from 
  --fork-block-number	The block number to fork from 
  --hostname         	The host to which to bind to for new connections (Defaults to 127.0.0.1 running locally, and 0.0.0.0 in Docker) 
  --port             	The port on which to listen for new connections (default: 8545)

node: Starts a JSON-RPC server on top of Hardhat Network
  1. Open a new terminal and deploy the smart contract in the localhost network
  • JavaScript
npx hardhat run --network localhost scripts/deploy.js
  • TypeScript
npx hardhat run --network localhost scripts/deploy.ts
  • If you are deploying on a network other than the local host, enter the following command:
npx hardhat run --network <your-network> scripts/deploy.js

The run command has the following options:

Usage: hardhat [GLOBAL OPTIONS] run [--no-compile] script

OPTIONS:

  --no-compile	Don't compile before running this task 

POSITIONAL ARGUMENTS:

  script	A js file to be run within hardhat's environment 

run: Runs a user-defined script after compiling the project