How does Hardhat support TypeScript and type safety?

Hardhat provides native support for TypeScript. Here are the main advantages and methods of using TypeScript:

1. Project Initialization

Create a project with TypeScript template:

bash
npx hardhat init
# Select "Create a TypeScript project"

2. Type-Safe Contract Interaction

Hardhat automatically generates type definitions:

typescript
import { ethers } from "hardhat";

async function main() {
  const Contract = await ethers.getContractFactory("MyContract");
  const contract = await Contract.deploy() as MyContract;
  
  // Type-safe function calls
  await contract.setValue(42);
  const value = await contract.value();
  
  console.log("Value:", value.toNumber());
}

3. Using TypeChain

TypeChain generates type definitions for contract ABIs:

bash
npm install --save-dev typechain @typechain/ethers-v5

Configure in hardhat.config.ts:

typescript
import "@typechain/hardhat";

Generated type definitions:

typescript
import { MyContract } from "../typechain-types";

const contract: MyContract = await contractFactory.deploy();

4. Type Safety in Tests

typescript
import { expect } from "chai";
import { ethers } from "hardhat";
import { MyContract } from "../typechain-types";

describe("MyContract", function () {
  let contract: MyContract;

  beforeEach(async function () {
    const ContractFactory = await ethers.getContractFactory("MyContract");
    contract = await ContractFactory.deploy();
    await contract.deployed();
  });

  it("should set value correctly", async function () {
    await contract.setValue(100);
    expect(await contract.value()).to.equal(100);
  });
});

5. Type-Safe Configuration Files

Use TypeScript configuration file hardhat.config.ts:

typescript
import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";

const config: HardhatUserConfig = {
  solidity: "0.8.19",
  networks: {
    sepolia: {
      url: process.env.SEPOLIA_RPC_URL || "",
      accounts: process.env.PRIVATE_KEY ? [process.env.PRIVATE_KEY] : []
    }
  }
};

export default config;

6. Environment Variable Type Definitions

typescript
// .env.d.ts
declare namespace NodeJS {
  interface ProcessEnv {
    SEPOLIA_RPC_URL: string;
    PRIVATE_KEY: string;
    ETHERSCAN_API_KEY: string;
  }
}

Advantages:

• Compile-time type checking
• Intelligent code completion
• Safer refactoring
• Reduced runtime errors
• Better code documentation
• More efficient team collaboration