PackageJson: Add packageManager field (#446)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

Author: TatsuyaYamamoto

source/package-json.d.ts

@@ -623,6 +623,25 @@ declare namespace PackageJson {
 		};
 	}
 
+	/**
+	Type for [`package.json` file used by the Node.js runtime](https://nodejs.org/api/packages.html#nodejs-packagejson-field-definitions).
+	*/
+	export interface NodeJsStandard {
+		/**
+		Defines which package manager is expected to be used when working on the current project. It can set to any of the [supported package managers](https://nodejs.org/api/corepack.html#supported-package-managers), and will ensure that your teams use the exact same package manager versions without having to install anything else than Node.js.
+
+		__This field is currently experimental and needs to be opted-in; check the [Corepack](https://nodejs.org/api/corepack.html) page for details about the procedure.__
+
+		@example
+		```json
+		{
+			"packageManager": "<package manager name>@<version>"
+		}
+		```
+		*/
+		packageManager?: string;
+	}
+
 	export interface PublishConfig {
 		/**
 		Additional, less common properties from the [npm docs on `publishConfig`](https://docs.npmjs.com/cli/v7/configuring-npm/package-json#publishconfig).
@@ -656,6 +675,7 @@ Type for [npm's `package.json` file](https://docs.npmjs.com/creating-a-package-j
 @category File
 */
 export type PackageJson =
+PackageJson.NodeJsStandard &
 PackageJson.PackageJsonStandard &
 PackageJson.NonStandardEntryPoints &
 PackageJson.TypeScriptConfiguration &

test-d/package-json.ts

@@ -16,6 +16,7 @@ expectType<PackageJson.Person[] | undefined>(packageJson.contributors);
 expectType<PackageJson.Person[] | undefined>(packageJson.maintainers);
 expectType<string[] | undefined>(packageJson.files);
 expectType<string | undefined>(packageJson.main);
+expectType<string | undefined>(packageJson.packageManager);
 expectType<string | Partial<Record<string, string>> | undefined>(packageJson.bin);
 expectType<string | undefined>(packageJson.types);
 expectType<string | undefined>(packageJson.typings);