Edit on val.town ↗

Migrate code

Use this as a reference, not a required sequence. Adapt the approach and code to suit the app and the user’s needs.

Read entrypoints, assets, imports, and tests. Keep the framework and adapt the maintained source directly; do not retain a Val Town copy plus scripts that rewrite it on deployment.

Use Node Functions when replacing Deno is the goal. Hono’s Netlify starter uses Edge Functions and Deno, a different runtime; choose it deliberately rather than treating it as a Node template.

A Netlify Node Function accepts a Web Request and returns a Response. An existing Hono app can be called directly. Keep routes in src/app.ts and export the Hono instance; save this as netlify/functions/api.ts:

import app from "../../src/app";
import type { Config } from "@netlify/functions";

export default (request: Request) => app.fetch(request);
export const config: Config = {
  path: ["/api", "/api/*"], excludedPath: ["/api/auth/*"],
};

If the Val Town file currently exports app.fetch, change it to export default app for this wrapper. The /api/auth/* exclusion reserves that path for the separate auth Function in the Access guide. If Hono already handles auth itself, remove the exclusion and do not add a second auth Function. The Hono app should define its actual /api/... paths. Preserve methods, status codes, headers, streaming, and error behavior. Install hono and @netlify/functions with npm; preserve the original major version while migrating.

For plain HTTP vals, put the original request-handling body in that default function. For Hono JSX, keep server rendering and the hono/jsx compiler settings; do not convert it into a SPA just to deploy.

Use the existing frontend or a Vite React app. Remove demo components and call server routes such as fetch("/api/items").

Example netlify.toml for a Vite frontend plus Node Functions:

[build]
  command = "npm run build"
  publish = "dist"

[functions]
  directory = "netlify/functions"
  node_bundler = "esbuild"
  included_files = ["content/templates/**"]

[[redirects]]
  from = "/app/*"
  to = "/index.html"
  status = 200

Only add that SPA fallback if the frontend uses client-side routes under /app/. It must not swallow API routes. For plain HTML/CSS/JS, publish the source asset directory instead; a build command is unnecessary unless files need compiling.

Val Town Replacement
npm: / package CDN imports Install the package; ordinary imports
esm.town imports Copy imported files/dependencies locally, with attribution
std/utils.readFile Build-time Node read or bundled runtime file
std/utils.listFiles, listFilesByPath Build-time readdir; runtime only for included files
std/utils.serveFile Published static files or an authenticated Function
std/utils.readFileTranspiled, fetchTranspiledJavaScript Vite/browser build
std/utils.serveImmutableFile, immutableFileUrl Build-generated hashed URLs
std/utils.hotReload Vite dev / Netlify dev
std/utils.httpEndpoint, emailAddress Explicit URL/address configuration

For runtime reads, declare files using included_files, then test the bundled path:

import { readFile } from "node:fs/promises";
import { resolve } from "node:path";
const template = await readFile(resolve("content/templates/mail.txt"), "utf8");

Use the included-files setting in the single netlify.toml above; do not add a second [functions] table. Resolve runtime paths from the project base directory and test the deployed bundle, not only netlify dev.

Use Node process.env for runtime env vars. Keep credentials, database clients, and private files out of the browser bundle. Function disk is not persistent application storage.

Keep Better Auth with a supported database adapter and preserve account mappings. Follow the database and Access guides for data and login changes. For MCP, preserve the client transport/tools and test a real reconnect; long-lived sessions may need a different host.

Run npm run build, the existing tests, and netlify dev, then deploy a test instance. Check direct nested URLs, refreshes, file reads, SSR, forms, API methods, and browser errors on that deployment. Document the working commands and runtime choice.

Last updated