1 files changed, 113 insertions, 0 deletions
diff --git a/src/js/build-esm.ts b/src/js/build-esm.ts
new file mode 100644
index 000000000..b3ece01a1
--- /dev/null
+++ b/src/js/build-esm.ts
@@ -0,0 +1,113 @@
+import { BuildConfig } from "bun";
+import fs from "fs";
+import path from "path";
+
+const OUT_DIR = path.join(import.meta.dir, "out/");
+const TMP_DIR = path.join(import.meta.dir, "out/tmp");
+
+// Because we do not load sourcemaps, we are not enabling identifiers + whitespace
+// minification on all files, just on the ones without logic or were already bundled
+const minifyList = [
+  "node/stream.js",
+  "node/crypto.js",
+
+  "node/assert.js",
+  "node/assert.strict.js",
+  "node/fs.promises.ts",
+  "node/path.js",
+  "node/path.posix.js",
+  "node/path.win32.js",
+  "node/stream.promises.js",
+  "node/stream.consumers.js",
+  "node/stream.web.js",
+];
+
+if (fs.existsSync(OUT_DIR + "/modules")) {
+  fs.rmSync(OUT_DIR + "/modules", { recursive: true });
+}
+if (fs.existsSync(OUT_DIR + "/modules_dev")) {
+  fs.rmSync(OUT_DIR + "/modules_dev", { recursive: true });
+}
+
+function readdirRecursive(root: string): string[] {
+  const files = fs.readdirSync(root, { withFileTypes: true });
+  return files.flatMap(file => {
+    const fullPath = path.join(root, file.name);
+    return file.isDirectory() ? readdirRecursive(fullPath) : fullPath;
+  });
+}
+
+const entrypoints = ["./bun", "./node", "./thirdparty"]
+  .flatMap(dir => readdirRecursive(path.join(import.meta.dir, dir)))
+  .filter(file => file.endsWith(".js") || (file.endsWith(".ts") && !file.endsWith(".d.ts")));
+
+const opts = {
+  target: "bun",
+  naming: {
+    entry: "[dir]/[name].[ext]",
+  },
+  root: import.meta.dir,
+  define: {
+    "process.platform": JSON.stringify(process.platform),
+    "process.arch": JSON.stringify(process.arch),
+  },
+} as const;
+
+const build_prod_minified = await Bun.build({
+  entrypoints: entrypoints.filter(file => minifyList.includes(file.slice(import.meta.dir.length + 1))),
+  minify: true,
+  ...opts,
+});
+
+const build_prod_unminified = await Bun.build({
+  entrypoints: entrypoints.filter(file => !minifyList.includes(file.slice(import.meta.dir.length + 1))),
+  minify: { syntax: true },
+  ...opts,
+});
+
+const build_dev = await Bun.build({
+  entrypoints: entrypoints,
+  minify: { syntax: true },
+  sourcemap: "external",
+  ...opts,
+});
+
+for (const [build, outdir] of [
+  [build_dev, path.join(OUT_DIR, "modules_dev")],
+  [build_prod_minified, path.join(OUT_DIR, "modules")],
+  [build_prod_unminified, path.join(OUT_DIR, "modules")],
+] as const) {
+  if (!build.success) {
+    console.error("Build failed");
+    throw new AggregateError(build.logs);
+  }
+
+  if (build.logs.length) {
+    console.log("Build has warnings:");
+    for (const log of build.logs) {
+      console.log(log);
+    }
+  }
+
+  for (const output of build.outputs) {
+    fs.mkdirSync(path.join(outdir, path.dirname(output.path)), { recursive: true });
+
+    if (output.kind === "entry-point" || output.kind === "chunk") {
+      const transformedOutput = (await output.text()).replace(/^(\/\/.*?\n)+/g, "");
+
+      if (transformedOutput.includes("$bundleError")) {
+        // attempt to find the string that was passed to $bundleError
+        const match = transformedOutput.match(/(?<=\$bundleError\(")(?:[^"\\]|\\.)*?(?="\))/);
+        console.error(`Build ${output.path} $bundleError: ${match?.[0] ?? "unknown"}`);
+        console.error(`DCE should have removed this function call, but it was not.`);
+        process.exit(1);
+      }
+
+      Bun.write(path.join(outdir, output.path), transformedOutput);
+    } else {
+      Bun.write(path.join(outdir, output.path), output);
+    }
+  }
+}
+
+console.log(`Bundled esm modules in ${performance.now().toFixed(2)}ms`);