Google TypeScript Style

Common errors

• Error: Failed to load config "gts" from "/path/to/project/.eslintrc.js"

  cause Attempting to use gts v7+ with the old ESLint `.eslintrc.js` configuration format.
  fix Migrate your ESLint configuration to the new flat config format in `eslint.config.js` as described in the v7.0.0 breaking changes. Example: `module.exports = [...require('gts')];`

• TS2728: Cannot find type definition file for 'node'.

  cause TypeScript's `lib` configuration in `tsconfig.json` is incorrect for the Node.js version being targeted.
  fix Ensure your `tsconfig.json`'s `compilerOptions.lib` includes appropriate types for your Node.js version. gts v6.0.2 fixed an issue related to `lib` support for Node 18+.

• warning " > gts@6.0.1" has unmet peer dependency "typescript@>=5".

  cause Your project's `typescript` version does not meet the `gts` peer dependency requirement.
  fix Upgrade TypeScript in your project to version 5 or greater. For example: `npm install typescript@latest --save-dev` or `yarn add typescript@latest --dev`.

• Error: A Promise-returning function provided to rule, 'no-floating-promises', is not marked async.

  cause An async function is being used as an ESLint rule callback without being explicitly marked as `async`, leading to a false positive for `no-floating-promises`.
  fix Mark the Promise-returning function as `async` in your ESLint configuration or custom rules to correctly handle asynchronous operations. If this is in your application code, ensure promises are handled.

Warnings

• breaking gts v7.0.0 migrated to ESLint's new flat config format (eslint.config.js). Projects using older `.eslintrc.js` files with gts may require updates to their ESLint configuration.
  Fix: Update your ESLint configuration file from `.eslintrc.js` to `eslint.config.js` and adapt it to the new flat config array format, typically using `module.exports = [...require('gts')];`.
• breaking gts v6.0.0 updated the default Prettier configuration to include `trailingComma: "all"`. This will reformat code for projects that previously used a different `trailingComma` setting or no explicit setting.
  Fix: Run `gts fix` to automatically reformat your codebase to the new `trailingComma: "all"` style. Review changes carefully.
• breaking gts v6.0.0 changed the `no-floating-promises` ESLint rule severity to `error`. This means any Promise returned from an async function that is not explicitly handled (e.g., awaited, `.then()`, `.catch()`) will now cause a build failure.
  Fix: Ensure all Promises returned from async functions or API calls are properly handled, either by awaiting them, chaining with `.then()`/`.catch()`, or explicitly ignoring them if intended (though generally discouraged). Example: `await someAsyncCall();` or `someAsyncCall().catch(err => console.error(err));`.
• breaking gts v6.0.0 set `composite: true` in `tsconfig-google.json`. This TypeScript configuration change affects how projects are built, particularly in monorepos or projects with multiple `tsconfig.json` files.
  Fix: Review your project's TypeScript build process and `tsconfig.json` files to ensure compatibility with `composite: true`. This may require adjusting `references` or build commands.
• gotcha gts requires Node.js version 18 or greater and TypeScript version 5 or greater as a peer dependency. Using older versions will lead to installation or runtime issues.
  Fix: Ensure your project's `package.json` specifies `engines.node` to `>=18` and `"typescript": ">=5"` in your `devDependencies` or `dependencies`. Upgrade Node.js and TypeScript if necessary.

Install

• npm install gts npm
• yarn add gts yarn
• pnpm add gts pnpm

Imports

• ESLint configuration
  wrong:

  import gts from 'gts';

  correct:

  module.exports = [...require('gts')];

  gts exports an array of ESLint configurations for consumption in `eslint.config.js` (new flat config format since v7) or `.eslintrc.js` (legacy). It is not typically imported for programmatic execution of functions or classes.
• CLI usage

  npx gts init

  The primary way to interact with gts for project setup and running lint/fix commands.
• Pre-commit hook

  repos:
    - repo: https://github.com/google/gts
      rev: '' # Use the sha / tag you want to point at
      hooks:
        - id: gts

  Integration with the pre-commit framework, specify a specific tag or commit SHA for `rev`.

Quickstart

Demonstrates how to initialize a new TypeScript project with `gts`, explaining the setup steps and how to run the generated linting, formatting, and compilation scripts.

// Initialize a new TypeScript project with gts
// Run these commands in your terminal:
// mkdir my-gts-project
// cd my-gts-project
// npm init -y
// npx gts init

// This command initializes gts, adding necessary devDependencies,
// creating configuration files (tsconfig.json, .eslintrc.js, .prettierrc.json),
// and adding standard scripts to your package.json (e.g., 'lint', 'fix', 'compile').
// It also creates a default `src/index.ts` if no source directory exists.

// Example src/index.ts content after initialization:
// export function greet(name: string): string {
//   return `Hello, ${name}!`;
// }
//
// async function main() {
//   const message = greet('TypeScript');
//   console.log(message);
//   // Example of an ignored promise that would now be an error in gts v6+
//   // Promise.resolve().then(() => console.log('async task'));
// }
//
// main().catch(console.error);

// To lint and fix issues after adding or modifying code:
// npm run lint
// npm run fix

// To compile your project:
// npm run compile