ChatGPT helped me replicate a code hosting service for esm.sh's playground.

[boomyao]

import { join, extname } from "https://deno.land/std/path/mod.ts";
import { exists } from "https://deno.land/std/fs/mod.ts";
import { transpile } from "https://deno.land/x/emit/mod.ts";

async function handleRequest(request: Request): Promise<Response> {
    const url = new URL(request.url);
    let path = url.pathname;

    // Serve index.html by default
    if (path === "/") {
        path = "/index.html";
    }

    const filePath = join("public", path);
    const fileExists = await exists(filePath);

    if (!fileExists) {
        return new Response("File not found", { status: 404 });
    }

    const ext = extname(filePath);

    if (ext === ".ts" || ext === ".tsx") {
        // Read TypeScript file
        // const source = await Deno.readTextFile(filePath);
        // Compile TypeScript to JavaScript
        const url = new URL(filePath, import.meta.url);
        const result = await transpile(filePath);
        const code = result.get(url.href)
        return new Response(code, {
            headers: { "content-type": "application/javascript" },
        });
    }

    // Serve other files directly
    const contentType = getContentType(ext) || "application/octet-stream";
    const content = await Deno.readFile(filePath);
    return new Response(content, { headers: { "content-type": contentType } });
}

function getContentType(ext: string): string | undefined {
    const types: { [key: string]: string } = {
        ".html": "text/html",
        ".js": "text/javascript",
        ".css": "text/css",
        ".png": "image/png",
        ".jpg": "image/jpeg",
    };
    return types[ext];
}

Deno.serve(handleRequest);