synopkg/site/src/content/docs/config/custom-types.mdx

Consistent dependency versions in large JavaScript Monorepos

---
title: customTypes
---

import { Badge } from "@astrojs/starlight/components";
import Details from "@site/components/details.astro";

Extend synopkg to manage other parts of package.json files than those provided by default.

Custom types behave indentically to the default [dependency types](REF_DEPENDENCY_TYPES) (such as `prod` or `peer`). When you define a custom type, you are adding to the list of valid names that can be passed to the:

- `--dependency-types` CLI option
- `dependencyTypes` property of [Version Groups](CONFIG_VERSION_GROUPS), [Semver Groups](CONFIG_SEMVER_GROUPS), and [Dependency Groups](CONFIG_DEPENDENCY_GROUPS).

This is how the default dependency types are defined:

```json title=".synopkgrc.json"
{
  "$schema": "./node_modules/synopkg/schema.json",
  "customTypes": {
    "dev": {
      "strategy": "versionsByName",
      "path": "devDependencies"
    },
    "local": {
      "strategy": "name~version",
      "namePath": "name",
      "path": "version"
    },
    "overrides": {
      "strategy": "versionsByName",
      "path": "overrides"
    },
    "peer": {
      "strategy": "versionsByName",
      "path": "peerDependencies"
    },
    "pnpmOverrides": {
      "strategy": "versionsByName",
      "path": "pnpm.overrides"
    },
    "prod": {
      "strategy": "versionsByName",
      "path": "dependencies"
    },
    "resolutions": {
      "strategy": "versionsByName",
      "path": "resolutions"
    }
  }
}
```

## \[name\] <Badge text="Required" variant="danger" />

The key of each custom type is its name, this is equivalent to the default names such as `prod` and `dev` and can be used in all of the same places those can:

1. `--dependency-types`
1. `versionGroup.dependencyTypes`
1. `semverGroup.dependencyTypes`
1. `dependencyGroup.dependencyTypes`

## \[name\].path <Badge text="Required" variant="danger" />

Where the version can be found in each package.json file, such as `engines`, `packageManager` or `some.nested.property`.

## \[name\].strategy <Badge text="Required" variant="danger" />

A strategy defines how synopkg should read and write dependency names and versions.

There are 3 to choose from:

### `name@version`

The name and version are combined in a single string. Commonly seen in package manager specifications.

```json
{
  "packageManager": "pnpm@7.27.0"
}
```

### `name~version`

The name and version are in different locations.

```json
{
  "name": "some-local-package",
  "version": "12.4.2"
}
```

### `versionsByName`

Typical dependency objects where keys are package names and values are version strings.

```json
{
  "pnpm": "10.10.0",
  "prettier": "3.5.3"
}
```