dtsroll

dtsroll is a CLI tool for bundling TypeScript declaration (.d.ts) files.

Why bundle .d.ts files?

• undefinedSmaller distributionundefined

  Tree-shaking removes unused code, keeping only what’s needed and reducing the output size.

• undefinedBundle in private dependenciesundefined

  Inline types from private dependencies (e.g., monorepo packages) that aren’t accessible to consumers.

• undefinedImprove TS performanceundefined

  Flattens multiple files into one, reducing TypeScript’s file resolution for type checking.

Install

npm install --save-dev dtsroll

Quick start

1. Compile your TypeScript code with declaration (.d.ts) files

   • If using the TypeScript compiler (tsc), enable declaration
   • If using Vite, use a plugin like vite-plugin-dts

2. Pass in the entry declaration file to dtsroll

   dtsroll --dry-run dist/index.d.ts
   

[!CAUTION]
dtsroll is designed to run on compiled output so it modifies files in-place.

• It will modify files you pass in, and files they import.
• Only pass in backed up or generated files
• Start with --dry-run

3. If the changes look good, remove the --dry-run flag:

   dtsroll dist/index.d.ts
   

Recommended setup

Running dtsroll without specifying input files will auto-detect them from package.json.

Update your package.json to reference .d.ts files and include dtsroll in the build step:

 {
     "name": "my-package",
     "exports": {
+        "types": "./dist/index.d.ts",
         "default": "./dist/index.js"
     },
     "scripts": {
+        "build": "tsc && dtsroll"
     }
 }

Externalization

By default, dtsroll decides which dependencies to bundle or keep external by analyzing the package.json file. Packages in devDependencies are bundled, and packages in other dependency types are externalized.

When there is no package.json file, you can specify packages to externalize with the --external flag.

Handling @types packages

Some packages need separate @types/* packages for type definitions. In this setup, typically:

• The main package is in dependencies.
• The corresponding @types/* package is in devDependencies.

Because the main package is in dependencies, dtsroll externalizes it. However, consumers of your package won’t get the type definitions for it because the @types/* package is only in devDependencies.

To fix this, dtsroll will display a warning suggesting you move the @types/* package out of devDependencies.

CLI

–help, -h

Display usage instructions.

–dry-run, -d

Simulate the bundling process without modifying the disk and logs what would happen.

–external, -e

If there is no package.json file, you can specify package names to exclude from the bundle.

[!NOTE]
This flag can only be used when there is no package.json. It’s better to define dependencies appropriately in package.json instead of using this flag.

–conditions, -C

Provide resolution conditions to target specific entry points in dependencies, similar to Node’s --conditions.

Node.js API

import { dtsroll } from 'dtsroll'

await dtsroll(options as {

    /**
     * CWD to find the package.json in
     * @default process.cwd()
     */
    cwd?: string

    /**
     * Defaults to auto-detecting d.ts files from package.json
     */
    inputs?: string[]

    /**
     * Only used if there's no package.json
     * Defaults to auto-detecting dependencies from package.json
     */
    external?: string[]

    conditions?: string[]

    dryRun?: boolean
})

Vite plugin

Use it in conjunction with a plugin that generates the initial declaration files like vite-plugin-dts.

import { defineConfig } from 'vitest/config'
import dts from 'vite-plugin-dts'
import { dtsroll } from 'dtsroll/vite'

export default defineConfig({
    // ...
    plugins: [
        // ...
        dts(),
        dtsroll()
    ]
})

Related

pkgroll

For package bundling (along with dts bundling), check out pkgroll.