Read the configuration file written in TypeScript

Mar 29, 2023 · 3 min

Sometimes you may want to read some configurations in your npm package or vscode extension. If the user’s project is in JavaScript, it is not difficult to achieve this by using dynamic imports:

const config = await import('config.js')

However, if it is a TypeScript configuration file, it is relatively complex.

Currently, many npm packages do not yet support TypeScript in their configuration files, such as webpack, and rollup also requires explicitly specifying the ts plugin to use rollup.config.ts.

However, the open-source c12 from unjs can easily help you obtain configuration files.

// Get loaded config
const { config } = await loadConfig({})

It will read the configuration file in the root directory by default.

However, in my scenario, I need a more flexible way to get the default export of a certain TypeScript file. Therefore, I used jiti, which is a dependency of c12.

const config: Record<string, string> = await jiti(configPath, {
  interopDefault: true,
  cache: false,
  requireCache: false,
  v8cache: false,
  esmResolve: true,

Besides ts files, jiti can also read the content of json files.

> cd ..