prefer module in exports

src/resolver/package_json.zig

@@ -1248,6 +1248,7 @@ pub const ESModule = struct {
     conditions: ConditionsMap,
     allocator: std.mem.Allocator,
     module_type: *options.ModuleType = undefined,
+    prefer_module_field_in_exports: bool,
 
     pub const Resolution = struct {
         status: Status = Status.Undefined,
@@ -1767,6 +1768,8 @@ pub const ESModule = struct {
                 var did_find_map_entry = false;
                 var last_map_entry_i: usize = 0;
 
+                var module_resolution: ?Resolution = null;
+
                 const slice = object.list.slice();
                 const keys = slice.items(.key);
                 for (keys, 0..) |key, i| {
@@ -1792,6 +1795,19 @@ pub const ESModule = struct {
                             r.module_type.* = .cjs;
                         }
 
+                        if (strings.eqlComptime(key, "module")) {
+                            if (r.prefer_module_field_in_exports) {
+                                r.module_type.* = .esm;
+                                return result;
+                            }
+
+                            // Node will not choose the "module" field in "exports". If it's not preferred, bun will
+                            // use the "module" field if no other conditions match. This behavior is similar to
+                            // the top-level "module" field.
+                            module_resolution = result;
+                            continue;
+                        }
+
                         return result;
                     }
 
@@ -1800,6 +1816,11 @@ pub const ESModule = struct {
                     }
                 }
 
+                if (module_resolution) |result| {
+                    r.module_type.* = .esm;
+                    return result;
+                }
+
                 if (r.debug_logs) |log| {
                     log.addNoteFmt("No keys matched", .{});
                 }

src/resolver/resolver.zig

@@ -1610,6 +1610,7 @@ pub const Resolver = struct {
                                     .allocator = r.allocator,
                                     .debug_logs = if (r.debug_logs) |*debug| debug else null,
                                     .module_type = &module_type,
+                                    .prefer_module_field_in_exports = r.prefer_module_field,
                                 };
 
                                 // Resolve against the path "/", then join it with the absolute
@@ -1875,6 +1876,7 @@ pub const Resolver = struct {
                                         debug
                                     else
                                         null,
+                                    .prefer_module_field_in_exports = r.prefer_module_field,
                                 };
 
                                 // Resolve against the path "/", then join it with the absolute
@@ -2853,6 +2855,7 @@ pub const Resolver = struct {
             .allocator = r.allocator,
             .debug_logs = if (r.debug_logs) |*debug| debug else null,
             .module_type = &module_type,
+            .prefer_module_field_in_exports = r.prefer_module_field,
         };
 
         const esm_resolution = esmodule.resolveImports(import_path, imports_map.root);

test/bundler/esbuild/default.test.ts

@@ -6836,4 +6836,77 @@ describe("bundler", () => {
       stdout: "5 9 2 7",
     },
   });
+  const fooNodeModule = {
+    "/node_modules/foo/package.json": `
+      {
+        "name": "foo",
+        "version": "2.0.0",
+        "exports": {
+          ".": {
+            "module": "./import.js",
+            "require": "./require.js",
+            "import": "./import.js"
+          }
+        }
+      }
+    `,
+    "/node_modules/foo/import.js": `
+      export const foo = 'import';
+    `,
+    "/node_modules/foo/require.js": `
+      export const foo = 'require';
+    `,
+  };
+  itBundled("default/ExportFieldWithModuleRuntimeImport", {
+    files: {
+      "/entry.js": `
+        import { foo } from 'foo';
+        console.log(foo);
+      `,
+      ...fooNodeModule,
+    },
+    bundling: false,
+    run: {
+      stdout: "import",
+    },
+  });
+  itBundled("default/ExportsFieldWithModuleBundleImport", {
+    files: {
+      "/entry.js": `
+        import { foo } from 'foo';
+        console.log(foo);
+      `,
+      ...fooNodeModule,
+    },
+    bundling: true,
+    run: {
+      stdout: "import",
+    },
+  });
+  itBundled("default/ExportsFieldWithModuleRuntimeRequire", {
+    files: {
+      "/entry.js": `
+        const { foo } = require('foo');
+        console.log(foo);
+      `,
+      ...fooNodeModule,
+    },
+    bundling: false,
+    run: {
+      stdout: "require",
+    },
+  });
+  itBundled("default/ExportsFieldWithModuleBundleRequire", {
+    files: {
+      "/entry.js": `
+        const { foo } = require('foo');
+        console.log(foo);
+      `,
+      ...fooNodeModule,
+    },
+    bundling: true,
+    run: {
+      stdout: "import",
+    },
+  });
 });