chore: write mjs server output files (#6225)

.changeset/clever-hairs-live.md

@@ -0,0 +1,5 @@
+---
+"@remix-run/dev": patch
+---
+
+write mjs server output files

integration/compiler-mjs-output-test.ts

@@ -0,0 +1,79 @@
+import { test, expect } from "@playwright/test";
+import * as fs from "node:fs";
+import * as path from "node:path";
+
+import { createFixtureProject, js } from "./helpers/create-fixture";
+
+let projectDir: string;
+
+test.beforeAll(async () => {
+  projectDir = await createFixtureProject({
+    future: { v2_routeConvention: true },
+    files: {
+      "package.json": js`
+        {
+          "name": "remix-template-remix",
+          "private": true,
+          "sideEffects": false,
+          "type": "module",
+          "scripts": {
+            "build": "node ../../../build/node_modules/@remix-run/dev/dist/cli.js build",
+            "dev": "node ../../../build/node_modules/@remix-run/dev/dist/cli.js dev",
+            "start": "node ../../../build/node_modules/@remix-run/serve/dist/cli.js build"
+          },
+          "dependencies": {
+            "@remix-run/node": "0.0.0-local-version",
+            "@remix-run/react": "0.0.0-local-version",
+            "@remix-run/serve": "0.0.0-local-version",
+            "isbot": "0.0.0-local-version",
+            "react": "0.0.0-local-version",
+            "react-dom": "0.0.0-local-version"
+          },
+          "devDependencies": {
+            "@remix-run/dev": "0.0.0-local-version",
+            "@types/react": "0.0.0-local-version",
+            "@types/react-dom": "0.0.0-local-version",
+            "typescript": "0.0.0-local-version"
+          },
+          "engines": {
+            "node": ">=14"
+          }
+        }      
+      `,
+      "remix.config.js": js`
+        export default {
+          serverModuleFormat: "esm",
+          serverBuildPath: "build/index.mjs",
+          future: {
+            v2_routeConvention: true,
+          },
+        };
+      `,
+      "app/routes/_index.jsx": js`
+        import { json } from "@remix-run/node";
+        import { useLoaderData, Link } from "@remix-run/react";
+
+        export function loader() {
+          return json("pizza");
+        }
+
+        export default function Index() {
+          let data = useLoaderData();
+          return (
+            <div>
+              {data}
+              <Link to="/burgers">Other Route</Link>
+            </div>
+          )
+        }
+      `,
+    },
+  });
+});
+
+test("can write .mjs server output module", () => {
+  let buildPath = path.resolve(projectDir, "build", "index.mjs");
+  expect(fs.existsSync(buildPath), "doesn't exist").toBe(true);
+  let contents = fs.readFileSync(buildPath, "utf8");
+  expect(contents, "no export statement").toContain("export {");
+});

packages/remix-dev/compiler/server/write.ts

@@ -11,7 +11,7 @@ export async function write(
   await fse.ensureDir(path.dirname(config.serverBuildPath));
 
   for (let file of outputFiles) {
-    if (file.path.endsWith(".js")) {
+    if (file.path.endsWith(".js") || file.path.endsWith(".mjs")) {
       // fix sourceMappingURL to be relative to current path instead of /build
       let filename = file.path.substring(file.path.lastIndexOf(path.sep) + 1);
       let escapedFilename = filename.replace(/\./g, "\\.");