better

transpile.ts

@@ -0,0 +1,57 @@
+import { CompilerOptions, transpile, TranspileOptions } from "jsr:@deno/emit";
+import denoJson from "./deno.json" with { type: "json" };
+
+const contentTypes = {
+    'js': "application/javascript; charset=utf-8",
+
+    // https://github.com/denoland/deno_ast/blob/ea1ccec37e1aa8e5e1e70f983a7ed1472d0e132a/src/media_type.rs#L117
+    'ts': "text/typescript; charset=utf-8",
+    'jsx': "text/jsx; charset=utf-8",
+    'tsx': "text/tsx; charset=utf-8",
+} as const;
+
+const transpileOptions = (extension: keyof typeof contentTypes, tsCode: string, targetUrlStr: string): TranspileOptions => ({
+    importMap: {
+        imports: denoJson.imports,
+    },
+    compilerOptions: denoJson.compilerOptions as CompilerOptions,
+    load(specifier) {
+        const correctContent = specifier === targetUrlStr;
+        return Promise.resolve({
+            kind: "module",
+            specifier,
+            content: correctContent ? tsCode : "",
+            headers: { "content-type": contentTypes[correctContent ? extension : 'js'] },
+        });
+    },
+});
+
+export default async function transpileResponse(response: Response, requestUrl: string, filepath?: string): Promise<Response> {
+    const url = new URL(`ts-serve:///${ requestUrl }`);
+    const pathname = filepath !== undefined ? filepath : url.pathname;
+    const extension = pathname.split('.').at(-1) ?? '';
+    if (response.status === 200 && (extension === 'ts' || extension === 'tsx' || extension === 'jsx')) {
+        const tsCode = await response.text();
+        const targetUrlStr = url.toString();
+        try {
+            const result = await transpile(url, transpileOptions(extension, tsCode, targetUrlStr));
+            const jsCode = result.get(targetUrlStr);
+            response.headers.delete("content-length");
+            response.headers.set("content-type", contentTypes.js);
+            return new Response(jsCode, {
+                status: response.status,
+                statusText: response.statusText,
+                headers: response.headers,
+            });
+        } catch (e) {
+            console.error('[transpileResponse]: Error transpiling!\n', e);
+            if (typeof e === 'string') {
+                return new Response('Internal Server Error', {
+                    status: 500,
+                    headers: response.headers,
+                });
+            }
+        }
+    }
+    return response;
+}