typechain

What is typechain?

TypeChain is a tool for generating TypeScript typings for Ethereum smart contracts. It helps developers interact with smart contracts in a type-safe manner, reducing runtime errors and improving the development experience.

What are typechain's main functionalities?

Generating TypeScript typings for smart contracts

This command generates TypeScript typings for smart contracts using the Ethers.js target. The generated typings are placed in the 'src/types' directory, and the input JSON files are located in the 'artifacts' directory.

npx typechain --target ethers-v5 --out-dir src/types './artifacts/**/*.json'

Using generated typings in a TypeScript project

This code demonstrates how to use the generated TypeScript typings in a TypeScript project. It imports the typings for a contract named 'MyContract', interacts with the contract using Ethers.js, and logs the result of calling a method on the contract.

import { MyContract } from './types/MyContract';

async function main() {
  const myContract: MyContract = await ethers.getContractAt('MyContract', '0x123...');
  const value = await myContract.myMethod();
  console.log(value);
}

Other packages similar to typechain

ethers

Ethers.js is a library for interacting with the Ethereum blockchain and its ecosystem. While it does not generate TypeScript typings for smart contracts, it provides a comprehensive set of tools for interacting with Ethereum, including contract interaction, wallet management, and more. TypeChain can generate typings specifically for use with Ethers.js.

web3

Web3.js is a collection of libraries that allow you to interact with a local or remote Ethereum node using HTTP, IPC, or WebSocket. Similar to Ethers.js, it does not generate TypeScript typings for smart contracts but provides a wide range of functionalities for interacting with the Ethereum blockchain. TypeChain can also generate typings for use with Web3.js.

truffle

Truffle is a development environment, testing framework, and asset pipeline for Ethereum. It provides a suite of tools for developing smart contracts, including compilation, deployment, and testing. While Truffle does not generate TypeScript typings, it can be used in conjunction with TypeChain to provide a complete development workflow.

README

🔌 TypeScript bindings for Ethereum smart contracts

💸 Enjoy using TypeChain? Consider funding development via GitCoin 💸

Used by the best:

Features ⚡

• static typing - you will never call not existing method again
• IDE support - works with any IDE supporting Typescript
• extendible - work with many different tools: ethers.js, hardhat, truffle, Web3.js or you can create your own target
• frictionless - works with simple, JSON ABI files as well as with Truffle/Hardhat artifacts

Installation

npm install --save-dev typechain

You will also need to install a desired target for example @typechain/ethers-v6. Learn more about targets

Take note, that code generated by TypeChain requires TypeScript version 4.3 or newer.

Packages 📦

Package	Version	Description	Examples
typechain		Core package	-
@typechain/ethers-v5		Ethers ver 5 support (⚠️ requires TS 4.0 >=)	example
@typechain/ethers-v6		Ethers ver 6 support (⚠️ requires TS 4.0 >=)	example
@typechain/starknet.js		Starknet.js ver 3.9
@typechain/truffle-v5		Truffle ver 5 support	example
@typechain/web3-v1		Web3 ver 1 support	example
@typechain/hardhat		Hardhat plugin	example-ethers example-truffle
@typechain/truffle-v4		Truffle ver 4 support (deprecated)	example
@typechain/ethers-v4		Ethers ver 4 support (deprecated)	example

eth-sdk

TypeChain generates only TypeScript typings (d.ts) files, if you're looking for "opinionated", "batteries included" solution check out our new project: eth-sdk. It generates typesafe, ready to use ethers.js wrappers and uses etherscan/sourcify to automatically get ABIs based only on smart contract addresses. Under the hood, eth-sdk relies on TypeChain.

Usage

CLI

Note: If you use hardhat just use hardhat plugin.

typechain --target=(ethers-v5|ethers-v6|truffle-v4|truffle-v5|web3-v1|path-to-custom-target) [glob]

• glob - pattern that will be used to find ABIs, remember about adding quotes: typechain "**/*.json", examples: ./abis/**/*.abi, ./abis/?(Oasis.abi|OasisHelper.abi).
• --target - ethers-v5, ethers-v6, truffle-v4, truffle-v5, web3-v1 or path to your custom target. Typechain will try to load package named: @typechain/${target}, so make sure that desired package is installed.
• --out-dir (optional) - put all generated files to a specific dir.
• --always-generate-overloads (optional) - some targets won't generate unnecessary types for overloaded functions by default, this option forces to always generate them
• --discriminate-types (optional) - ethers-v5 and ethers-v6 will add an artificial field contractName that helps discriminate between contracts

TypeChain always will rewrite existing files. You should not commit them. Read more in FAQ section.

Example:

typechain --target ethers-v6 --out-dir app/contracts './node_modules/neufund-contracts/build/contracts/*.json'

Videos

• Devcon5 Video (2019)

Getting started 📚

Motivation

Interacting with blockchain in Javascript is a pain. Developers need to remember not only a name of a given smart contract method or event but also it's full signature. This wastes time and might introduce bugs that will be triggered only in runtime. TypeChain solves these problems (as long as you use TypeScript).

How does it work?

TypeChain is a code generator - provide ABI file and name of your blockchain access library (ethers/truffle/web3.js) and you will get TypeScript typings compatible with a given library.

Step by step guide

Install TypeChain with npm install --save-dev typechain and install desired target.

Run typechain --target=your_target (you might need to make sure that it's available in your path if you installed it only locally), it will automatically find all .abi files in your project and generate Typescript classes based on them. You can specify your glob pattern: typechain --target=your_target "**/*.abi.json". node_modules are always ignored. We recommend git ignoring these generated files and making typechain part of your build process.

That's it! Now, you can simply import typings, check out our examples for more details.

Targets 🎯

Ethers.js v6

Use ethers-v6 target to generate wrappers for ethers.js lib. To make it work great with Hardhat, use Hardhat plugin.

If you use nodenext aka node16modules flip the flag --node16-modules to generate compatible typings.

If you are using Ethers.js v5, use the @typechain/ethers-v5 target.

If you're using Ethers.js v4, you can find legacy @typechain/ethers-v4 target on npm and commit db551b5.

Truffle v5

Truffle target is great when you use truffle contracts already. Check out truffle-typechain-example for more details.

Now you can simply use your contracts as you did before and get full type safety, yay!

Web3 v1

Generates typings for contracts compatible with latest stable Web3.js version. Typings for library itself are now part of the Web3 1.0.0 library so nothing additional is needed. For now it needs explicit cast as shown here, this will be fixed after improving official typings.

NatSpec support

If you provide solidity artifacts rather than plain ABIs as an input, TypeChain can generate NatSpec comments directly to your typings which enables simple access to docs while coding.

Your own target

This might be useful when you're creating a library for users of your smartcontract and you don't want to lock yourself into any API provided by Web3 access providing library. You can generate basically any code (even for different languages than TypeScript!) that based on smartcontract's ABI.

FAQ 🤔

Q: Should I commit generated files to my repository?

A: NO — we believe that no generated files should go to git repository. You should git ignore them and make typechain run automatically for example in post install hook in package.json:

"postinstall":"typechain"

When you update ABI, just regenerate files with TypeChain and Typescript compiler will find any breaking changes for you.

Q: How do I customize generated code?

A: You can create your own target and generate basically any code.

Q: Generated files won't match current codestyle of my project :(

A: We will automatically format generated classes with prettier to match your coding preferences (just make sure to use .prettierrc file).

Furthermore, TypeChain will silent eslint and tslint errors for generated files.

Usage as API

import { runTypeChain, glob } from 'typechain'

async function main() {
  const cwd = process.cwd()
  // find all files matching the glob
  const allFiles = glob(cwd, [`${config.paths.artifacts}/!(build-info)/**/+([a-zA-Z0-9_]).json`])

  const result = await runTypeChain({
    cwd,
    filesToProcess: allFiles,
    allFiles,
    outDir: 'out directory',
    target: 'target name',
  })
}

main().catch(console.error)

If you don't care about incremental generation just specify the same set of files for filesToProcess and allFiles. For incremental generation example read the source code of hardhat plugin.

Contributing

Check out our contributing guidelines

Licence

Kris Kaczor (krzkaczor) MIT | Github | Twitter