---
url: /advanced/hooks.md
---
# Hooks

Inspired by [unbuild](https://github.com/unjs/unbuild), `tsdown` supports a flexible hooks system that allows you to extend and customize the build process. While we recommend using the [plugin system](./plugins.md) for most build-related extensions, hooks provide a convenient way to inject Rolldown plugins or perform additional tasks at specific stages of the build lifecycle.

## Usage

You can define hooks in your configuration file in two ways:

### Passing an Object

Define your hooks as an object, where each key is a hook name and the value is a function:

```ts [tsdown.config.ts]
import { defineConfig } from 'tsdown'

export default defineConfig({
  hooks: {
    'build:done': async () => {
      await doSomething()
    },
  },
})
```

### Passing a Function

Alternatively, you can pass a function that receives the hooks object, allowing you to register hooks programmatically:

```ts [tsdown.config.ts]
import { defineConfig } from 'tsdown'

export default defineConfig({
  hooks(hooks) {
    hooks.hook('build:prepare', () => {
      console.log('Hello World')
    })
  },
})
```

For more details on how to use the hooks, refer to the [hookable](https://github.com/unjs/hookable) documentation.

## Available Hooks

For detailed type definitions, see [`src/features/hooks.ts`](https://github.com/rolldown/tsdown/blob/main/src/features/hooks.ts).

### `build:prepare`

Invoked before each tsdown build starts. Use this hook to perform setup or preparation tasks.

### `build:before`

Invoked before each Rolldown build. For dual-format builds, this hook is called for each format. Useful for configuring or modifying the build context before bundling.

### `build:done`

Invoked after each tsdown build completes. Use this hook for cleanup or post-processing tasks.