fix: support package.json browser field

README.md

@@ -19,6 +19,7 @@ Polyfills nodejs builtin modules and globals for the browser.
 -   Offers CJS and ESM builds
 -   Full TypeScript & JavaScript support
 -   Supports `node:` protocol
+-   Supports [`browser` field in `package.json`](https://github.com/defunctzombie/package-browser-field-spec)
 -   Optionally injects globals
 -   Optionally provides empty fallbacks
 

src/lib/plugin.ts

@@ -1,6 +1,8 @@
 import { builtinModules } from 'node:module';
 import path from 'node:path';
 
+import { loadPackageJSON } from 'local-pkg';
+
 import { getCachedPolyfillContent, getCachedPolyfillPath } from './polyfill.js';
 import { escapeRegex, commonJsTemplate, normalizeNodeBuiltinPath } from './utils/util.js';
 
@@ -113,14 +115,21 @@ export const nodeModulesPolyfillPlugin = (options: NodePolyfillsOptions = {}): P
 			const filter = new RegExp(`^(?:node:)?(?:${bundledModules.map(escapeRegex).join('|')})$`);
 
 			const resolver = async (args: OnResolveArgs): Promise<OnResolveResult | undefined> => {
-				const moduleName = normalizeNodeBuiltinPath(args.path);
-
 				const emptyResult = {
 					namespace: emptyNamespace,
 					path: args.path,
 					sideEffects: false,
 				};
 
+				// https://github.com/defunctzombie/package-browser-field-spec
+				if (initialOptions.platform === 'browser') {
+					const packageJson = await loadPackageJSON(args.resolveDir);
+					const browserFieldValue = packageJson?.browser?.[args.path];
+					if (browserFieldValue !== undefined) return;
+				}
+
+				const moduleName = normalizeNodeBuiltinPath(args.path);
+
 				const fallbackResult =
 					fallback === 'empty'
 						? emptyResult // Stub it out with an empty module

tests/fixtures/input/browserFieldAlias/alias.ts

@@ -0,0 +1,3 @@
+export default {
+	THIS_CAME_FROM_AN_ALIASED_MODULE: true,
+};

tests/fixtures/input/browserFieldAlias/browserFieldAlias.ts

@@ -0,0 +1,4 @@
+// eslint-disable-next-line unicorn/prefer-node-protocol, n/no-deprecated-api
+import * as constants from 'constants';
+
+console.log(constants);

tests/fixtures/input/browserFieldAlias/package.json

@@ -0,0 +1,5 @@
+{
+	"browser": {
+		"constants": "./alias.ts"
+	}
+}

tests/fixtures/input/browserFieldFalse/browserFieldFalse.ts

@@ -0,0 +1,4 @@
+// eslint-disable-next-line unicorn/prefer-node-protocol, n/no-deprecated-api
+import * as constants from 'constants';
+
+console.log(constants);

tests/fixtures/input/browserFieldFalse/package.json

@@ -0,0 +1,5 @@
+{
+	"browser": {
+		"constants": false
+	}
+}

tests/fixtures/input/browserFieldMissing/browserFieldMissing.ts

@@ -0,0 +1,4 @@
+// eslint-disable-next-line unicorn/prefer-node-protocol, n/no-deprecated-api
+import * as constants from 'constants';
+
+console.log(constants);

tests/fixtures/input/browserFieldMissing/package.json

@@ -0,0 +1 @@
+{}