Go bonkers on the global vars

.eslintrc.js

@@ -83,6 +83,21 @@ const restrictedImports = [
 	},
 ];
 
+const restrictedGlobals = [
+	{
+		name: 'SCRIPT_DEBUG',
+		message: 'Use globalThis.SCRIPT_DEBUG',
+	},
+	{
+		name: 'IS_GUTENBERG_PLUGIN',
+		message: 'Use globalThis.IS_GUTENBERG_PLUGIN',
+	},
+	{
+		name: 'IS_WORDPRESS_CORE',
+		message: 'Use globalThis.IS_WORDPRESS_CORE',
+	},
+];
+
 module.exports = {
 	root: true,
 	extends: [
@@ -92,6 +107,7 @@ module.exports = {
 	],
 	globals: {
 		wp: 'off',
+		globalThis: 'readonly',
 	},
 	settings: {
 		jsdoc: {
@@ -122,6 +138,7 @@ module.exports = {
 				paths: restrictedImports,
 			},
 		],
+		'no-restricted-globals': [ 'error', ...restrictedGlobals ],
 		'@typescript-eslint/no-restricted-imports': [
 			'error',
 			{

packages/private-apis/src/implementation.js

@@ -66,7 +66,7 @@ let allowReRegistration;
 // Let's default to true, then. Try/catch will fall back to "true" even if the
 // environment variable is not explicitly defined.
 try {
-	allowReRegistration = process.env.IS_WORDPRESS_CORE ? false : true;
+	allowReRegistration = globalThis.IS_WORDPRESS_CORE ? false : true;
 } catch ( error ) {
 	allowReRegistration = true;
 }

tools/webpack/shared.js

@@ -64,13 +64,13 @@ const plugins = [
 	process.env.WP_BUNDLE_ANALYZER && new BundleAnalyzerPlugin(),
 	new DefinePlugin( {
 		// Inject the `IS_GUTENBERG_PLUGIN` global, used for feature flagging.
-		'process.env.IS_GUTENBERG_PLUGIN':
+		'globalThis.IS_GUTENBERG_PLUGIN':
 			process.env.npm_package_config_IS_GUTENBERG_PLUGIN,
 		// Inject the `IS_WORDPRESS_CORE` global, used for feature flagging.
-		'process.env.IS_WORDPRESS_CORE':
+		'globalThis.IS_WORDPRESS_CORE':
 			process.env.npm_package_config_IS_WORDPRESS_CORE,
 		// Inject the `SCRIPT_DEBUG` global, used for dev versions of JavaScript.
-		SCRIPT_DEBUG: mode === 'development',
+		'globalThis.SCRIPT_DEBUG': mode === 'development',
 	} ),
 	mode === 'production' && new ReadableJsAssetsWebpackPlugin(),
 ];

typings/gutenberg-env/index.d.ts

@@ -1,17 +1,14 @@
-interface Environment {
-	NODE_ENV: unknown;
-	IS_GUTENBERG_PLUGIN?: boolean;
-	IS_WORDPRESS_CORE?: boolean;
-}
-
 declare namespace NodeJS {
-	export interface ProcessEnv extends Environment {}
-
-	export interface Process {
-		env: ProcessEnv;
+	interface ProcessEnv {
+		readonly NODE_ENV?: 'production' | 'development' | 'test';
+	}
+	interface Process {
+		env: NodeJS.ProcessEnv;
 	}
 }
 
 declare var process: NodeJS.Process;
 
-declare var SCRIPT_DEBUG: boolean;
+declare var SCRIPT_DEBUG: undefined | boolean;
+declare var IS_GUTENBERG_PLUGIN: undefined | boolean;
+declare var IS_WORDPRESS_CORE: undefined | boolean;