fix #4187: browser package.json regression

evanw · evanw · commit 223ddc6a5f1b · 2025-05-26T23:07:07.000-04:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+* Fix a regression with `browser` in `package.json` ([#4187](https://github.com/evanw/esbuild/issues/4187))
+
+    The fix to [#4144](https://github.com/evanw/esbuild/issues/4144) in version 0.25.3 introduced a regression that caused `browser` overrides specified in `package.json` to fail to override relative path names that end in a trailing slash. That behavior change affected the `axios@0.30.0` package. This regression has been fixed, and now has test coverage.
+
 * Add support for certain keywords as TypeScript tuple labels ([#4192](https://github.com/evanw/esbuild/issues/4192))
 
     Previously esbuild could incorrectly fail to parse certain keywords as TypeScript tuple labels that are parsed by the official TypeScript compiler if they were followed by a `?` modifier. These labels included `function`, `import`, `infer`, `new`, `readonly`, and `typeof`. With this release, these keywords will now be parsed correctly. Here's an example of some affected code:
diff --git a/internal/bundler_tests/bundler_packagejson_test.go b/internal/bundler_tests/bundler_packagejson_test.go
@@ -3069,3 +3069,35 @@ func TestConfusingNameCollisionsIssue4144(t *testing.T) {
 		},
 	})
 }
+
+// https://github.com/evanw/esbuild/issues/4187
+func TestPackageJsonBrowserMatchingTrailingSlashIssue4187(t *testing.T) {
+	packagejson_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.js": `
+				import axios from "axios"
+			`,
+			"/node_modules/axios/package.json": `
+				{
+					"browser": {
+						"./node/index.js": "./browser/index.js"
+					}
+				}
+			`,
+			"/node_modules/axios/index.js": `
+				module.exports = require('./node/');
+			`,
+			"/node_modules/axios/node/index.js": `
+				module.exports = { get: () => new Promise('Node') }
+			`,
+			"/node_modules/axios/browser/index.js": `
+				module.exports = { get: () => new Promise('Browser') }
+			`,
+		},
+		entryPaths: []string{"/entry.js"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/out.js",
+		},
+	})
+}
diff --git a/internal/bundler_tests/snapshots/snapshots_packagejson.txt b/internal/bundler_tests/snapshots/snapshots_packagejson.txt
@@ -308,6 +308,26 @@ var require_main_browser = __commonJS({
 var import_demo_pkg = __toESM(require_main_browser());
 console.log((0, import_demo_pkg.default)());
 
+================================================================================
+TestPackageJsonBrowserMatchingTrailingSlashIssue4187
+---------- /out.js ----------
+// node_modules/axios/browser/index.js
+var require_browser = __commonJS({
+  "node_modules/axios/browser/index.js"(exports, module) {
+    module.exports = { get: () => new Promise("Browser") };
+  }
+});
+
+// node_modules/axios/index.js
+var require_axios = __commonJS({
+  "node_modules/axios/index.js"(exports, module) {
+    module.exports = require_browser();
+  }
+});
+
+// entry.js
+var import_axios = __toESM(require_axios());
+
 ================================================================================
 TestPackageJsonBrowserNoExt
 ---------- /Users/user/project/out.js ----------
diff --git a/internal/resolver/resolver.go b/internal/resolver/resolver.go
@@ -1012,6 +1012,21 @@ func (r resolverQuery) resolveWithoutSymlinks(sourceDir string, sourceDirInfo *d
 			strings.HasSuffix(importPath, "/.") ||
 			strings.HasSuffix(importPath, "/..")
 
+		// Check the "browser" map
+		if importDirInfo := r.dirInfoCached(r.fs.Dir(absPath)); importDirInfo != nil {
+			if remapped, ok := r.checkBrowserMap(importDirInfo, absPath, absolutePathKind); ok {
+				if remapped == nil {
+					return &ResolveResult{PathPair: PathPair{Primary: logger.Path{Text: absPath, Namespace: "file", Flags: logger.PathDisabled}}}
+				}
+				if remappedResult, ok, diffCase, sideEffects := r.resolveWithoutRemapping(importDirInfo.enclosingBrowserScope, *remapped); ok {
+					result = ResolveResult{PathPair: remappedResult, DifferentCase: diffCase, PrimarySideEffectsData: sideEffects}
+					hasTrailingSlash = false
+					checkRelative = false
+					checkPackage = false
+				}
+			}
+		}
+
 		if hasTrailingSlash {
 			if absolute, ok, diffCase := r.loadAsDirectory(absPath); ok {
 				checkPackage = false
@@ -1020,20 +1035,6 @@ func (r resolverQuery) resolveWithoutSymlinks(sourceDir string, sourceDirInfo *d
 				return nil
 			}
 		} else {
-			// Check the "browser" map
-			if importDirInfo := r.dirInfoCached(r.fs.Dir(absPath)); importDirInfo != nil {
-				if remapped, ok := r.checkBrowserMap(importDirInfo, absPath, absolutePathKind); ok {
-					if remapped == nil {
-						return &ResolveResult{PathPair: PathPair{Primary: logger.Path{Text: absPath, Namespace: "file", Flags: logger.PathDisabled}}}
-					}
-					if remappedResult, ok, diffCase, sideEffects := r.resolveWithoutRemapping(importDirInfo.enclosingBrowserScope, *remapped); ok {
-						result = ResolveResult{PathPair: remappedResult, DifferentCase: diffCase, PrimarySideEffectsData: sideEffects}
-						checkRelative = false
-						checkPackage = false
-					}
-				}
-			}
-
 			if checkRelative {
 				if absolute, ok, diffCase := r.loadAsFileOrDirectory(absPath); ok {
 					checkPackage = false
