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.
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);
}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.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 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.
🔌 Typescript bindings for Ethereum smartcontracts
Contributed with:
truffle,Web3.js 1.0, ethers.js, Web3.js 0.20.xnpm install --save-dev typechain
yarn add --dev typechain
typechain --target=(truffle|web3-1.0.0|legacy) [glob]
glob - pattern that will be used to find ABIs, remember about adding quotes: typechain "**/*.json"--target - truffle, web3-1.0.0, ethers or legacy--outDir - put all generated files to a specific dirTypechain always will rewrite existing files. You should not commit them. Read more in FAQ section.
Example:
typechain --target --outDir app/contracts './node_modules/neufund-contracts/build/contracts/*.json'
Typechain is a plugin to ts-generator meaning that you can as well create unified config.
ts-generator.json file:
[
{
"generator": "typechain",
"files": "./build/**/*.json",
"target": "truffle"
}
]
then just run ts-generator (you need to have ts-generator installed in your project).
This can be a great way to run more code generation plugins (css modules types, graphql types etc. ) at the same time.
Interacting with blockchain in Javascript is a pain. Web3 interface is sluggish and when using it with Typescript it gets even worse. Often, you can't be sure what given method call will actually do without looking at ABI file. TypeChain is here to solve these problems (as long as you use Typescript).
TypeChain is code generator - provide ABI file and you will get Typescript class with flexible interface for interacting with blockchain. Depending on the target parameter it can generate typings for truffle, web3 1.0.0 or web3 0.20.x (legacy target).
Install typechain with yarn add --dev typechain.
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, just import contract bindings as any other file import { MyAwesomeContract } from './contracts/MyAwesomeContract' and start interacting with it. We use named exports because of
this.
Truffle target is great when you use truffle contracts already. Check out truffle-typechain-example for more details. It require installing typings for truffle library itself.
Now you can simply use your contracts as you did before and get full type safety, yay!
Generates typings for contracts compatible with latest Web3.js version. Typings for library itself are now part of 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.
Use ethers target to generate wrappers for ethers.js lib.
This was default and only target for typechain 0.2.x. It requires Web3.js 0.20.x to be installed in your project and it generates promise based wrappers. It's nice upgrade comparing to raw callbacks but in the near future Typechain will support Web3js 1.0 target.
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.
A: You can create your own class that extends generated one and adds additional methods etc.
Currently we discuss various ideas around extendibility including APIs files (adding semantics to ABIs for covering popular cases like working with dates) or using user-defined templates for generated code.
A: We will automatically format generated classes with prettier to match your coding preferences (just make sure to use .prettierrc file).
Furthermore, we will silent tslint for generated files with /* tslint:disable */ comments.
You may want to use ts-generator api to kick off whole process by api:
import { tsGen } from "ts-generator";
import { Typechain } from "typechain";
async function main() {
await tsGen({ cwd }, new Typechain({ cwd, rawConfig: { files: "your-glob-here", outDir: "optional out dir path" } }));
}
yarn # install all dependencies
yarn test # runs tests + linting
DEBUG=typechain typechain
FAQs
🔌 TypeScript bindings for Ethereum smartcontracts
The npm package typechain receives a total of 35,190 weekly downloads. As such, typechain popularity was classified as popular.
We found that typechain demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 2 open source maintainers collaborating on the project.
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