Config File

By default, tsdown will search for a configuration file by looking in the current working directory and traversing upward through parent directories until it finds one. It supports the following file names:

• tsdown.config.ts
• tsdown.config.mts
• tsdown.config.cts
• tsdown.config.js
• tsdown.config.mjs
• tsdown.config.cjs
• tsdown.config.json
• tsdown.config

Additionally, you can define your configuration directly in the tsdown field of your package.json file.

Writing a Config File

The configuration file allows you to define and customize your build settings in a centralized and reusable way. Below is a simple example of a tsdown configuration file:

tsdown.config.ts

import { defineConfig } from 'tsdown'

export default defineConfig({
  entry: 'src/index.ts',
})

Building Multiple Outputs

tsdown also supports returning an array of configurations from the config file. This allows you to build multiple outputs with different settings in a single run. For example:

tsdown.config.ts

import { defineConfig } from 'tsdown'

export default defineConfig([
  {
    entry: 'src/entry1.ts',
    platform: 'node',
  },
  {
    entry: 'src/entry2.ts',
    platform: 'browser',
  },
])

Specifying a Custom Config File

If your configuration file is located elsewhere or has a different name, you can specify its path using the --config (or -c) option:

tsdown --config ./path/to/config

Disabling the Config File

To disable loading a configuration file entirely, use the --no-config option:

tsdown --no-config

This is useful if you want to rely solely on command-line options or default settings.

Config Loaders

tsdown supports multiple config loaders to accommodate various file formats. You can select a config loader using the --config-loader option. The available loaders are:

• auto (default): Utilizes native runtime loading for TypeScript if supported; otherwise, defaults to unconfig.
• native: Loads TypeScript configuration files using native runtime support. Requires a compatible environment, such as the latest Node.js, Deno, or Bun.
• unconfig: Loads configuration files with the unconfig library, ensuring broad compatibility across different runtimes.
• unrun (experimental): Loads configuration files using the unrun library, which provides similar compatibility as unconfig but with more performances. Install the unrun package to use this loader.

TIP

Node.js does not natively support importing TypeScript files without specifying the file extension. If you are using Node.js and want to load a TypeScript config file without including the .ts extension, consider using the unconfig or unrun loader for seamless compatibility.

Extending Vite or Vitest Config (Experimental)

tsdown provides an experimental feature to extend your existing Vite or Vitest configuration files. This allows you to reuse specific configuration options, such as resolve and plugins, while ignoring others that are not relevant to tsdown.

To enable this feature, use the --from-vite option:

tsdown --from-vite        # Load vite.config.*
tsdown --from-vite vitest # Load vitest.config.*

WARNING

This feature is experimental and may not support all Vite or Vitest configuration options. Only specific options, such as resolve and plugins, are reused. Use with caution and test thoroughly in your project.

TIP

Extending Vite or Vitest configurations can save time and effort if your project already uses these tools, allowing you to build upon your existing setup without duplicating configuration.

Reference

For a full list of available configuration options, refer to the Config Options Reference. This includes detailed explanations of all supported fields and their usage.