@dnd-mapp/package-builder

Prepares the dist directory that gets published to npm.

The tool writes a trimmed package.json next to your build output, copies the files that consumers need, and checks that the exports and bin fields point to files that exist.

Requirements

• A Node.js version that matches the engines field of the package.
• A package that publishes from a dist directory, with publishConfig.directory set to dist.

Installation

pnpm add --save-dev @dnd-mapp/package-builder

Usage

Build your package into dist first. Then run the prepare-dist command from the root of your project. The easiest way is to chain it in the prepublishOnly script.

{
    "publishConfig": {
        "directory": "dist"
    },
    "scripts": {
        "build": "tsdown",
        "prepublishOnly": "pnpm build && prepare-dist"
    }
}

The command works on the package in the current working directory. It runs these steps:

1. Reads the config and your package.json.
2. Assembles the package in a staging directory, .tmp.
3. Writes a trimmed package.json and copies the files that you include.
4. Checks that every file in exports and bin exists in the staging directory.
5. Replaces dist with the staging directory.

If a step fails, the command removes the staging directory and leaves dist as it was, so a failed run never leaves a partial dist behind.

Add .tmp to your .gitignore file, because the staging directory is created in your project root.

The published manifest

The package.json in dist is a copy of your own, without the fields that only matter during development. By default the command removes $schema, scripts, devDependencies, and devEngines. It also removes publishConfig.directory, so the published package does not point at a nested dist directory.

The exports and bin paths in your package.json are relative to dist, because that is the root of the published package. For example, use ./index.js and not ./dist/index.js.

Configuration

Create .prepare-distrc.json in the root of your project to change what the command does. The file is optional. Without it, the command uses the defaults below.

{
    "$schema": "./node_modules/@dnd-mapp/package-builder/prepare-dist.schema.json",
    "clean": false,
    "include": ["README.md", "LICENSE", "prepare-dist.schema.json"]
}

Key	Type	Default	Description
clean	boolean	true	Deletes the files already in dist when true, and keeps them when false
removedFields	string[]	["$schema", "scripts", "devDependencies", "devEngines"]	Fields of package.json that are left out of the published manifest
include	string[]	["configs", "CHANGELOG.md", "README.md", "LICENSE"]	Files and directories, relative to the project root, to copy

Every key is optional. A key that you leave out keeps its default. A list that you set replaces the default list, and it is not merged with it.

Keeping the build output

With clean set to true, the command replaces dist and deletes the files that your build wrote there. Set clean to false to keep them. This is the setting to use when you build into dist.

In that case the command starts the staging directory from a copy of dist. It then writes the manifest and the included files over the copy. Files with the same path are overwritten. If dist does not exist yet, the command starts with an empty directory.

Editor validation

The package ships a JSON schema that lets editors check .prepare-distrc.json while you type. Point the $schema key at the copy in node_modules, as in the example above.

The schema is also listed in the exports field. You can resolve it by package name, for example with import.meta.resolve('@dnd-mapp/package-builder/prepare-dist.schema.json').

Errors

The command stops before it touches dist when the config is not valid. It reports one of these errors:

• Failed to read ".prepare-distrc.json" when the file exists but cannot be read.
• Failed to parse ".prepare-distrc.json" when the file is not valid JSON.
• Invalid ".prepare-distrc.json": ... when the content is not an object, has an unknown key, or has a value of the wrong type.

It also fails with The exports and bin fields point to files that are not published when a target is missing from the staging directory. The message lists every missing file.

Programmatic API

The package also exports the building blocks of the command. Importing the package does not run anything.

import { loadConfig, createPublishManifest } from '@dnd-mapp/package-builder';

const config = await loadConfig();
const manifest = await createPublishManifest(config.removedFields);

Export	Description
CONFIG_FILE	The name of the config file, .prepare-distrc.json
loadConfig	Reads the config file and applies the defaults
createPublishManifest	Reads package.json and removes the fields that are not published
writeManifest	Writes a manifest to package.json in a directory
verifyExports	Checks that the files in exports and bin exist in a directory
collectExportTargets	Lists the local files that an exports field points to
collectBinTargets	Lists the local files that a bin field points to

The Config and Manifest types are exported as well.

Changelog

Notable changes for consumers of this package are listed in the changelog.

Contributing

Contributions are welcome. See the contributing guide for details.

License

MIT © D&D Mapp