App.js Micro Web Framework

Common errors

• TypeError: App is not a constructor

  cause Attempting to instantiate 'App' after importing it incorrectly using ES module syntax (e.g., `import App from 'app';`) or named destructuring from a CJS module that exports a single constructor.
  fix Use CommonJS require syntax for `App`: `const App = require('app');`

• SyntaxError: Cannot use import statement outside a module

  cause Attempting to use ES module `import` syntax in a file that Node.js interprets as a CommonJS module (e.g., a `.js` file without `"type": "module"` in `package.json`, or an older Node.js environment).
  fix Replace `import` statements with CommonJS `require()` syntax: `const App = require('app');`

• Error: Cannot find module 'connect'

  cause The 'connect' package, a direct dependency of 'app', is not installed or not resolvable in the project's `node_modules`.
  fix Install 'connect' explicitly: `npm install connect` to ensure it is available for 'app'.

Warnings

• breaking This package is explicitly abandoned and has not been updated since circa 2011 (version 0.1.0). It is not compatible with modern Node.js versions or contemporary JavaScript features (e.g., async/await, ES Modules).
  Fix: Migrate to an actively maintained and modern Node.js web framework like Express, Fastify, or Koa. Do not use for new development.
• gotcha The framework exclusively uses CommonJS (`require()`) for module imports and exports. It does not support ES Modules (`import`/`export` syntax), which became standard much later.
  Fix: Ensure your project uses CommonJS syntax throughout or use a build tool like Webpack or Rollup configured for CJS output if integrating into a legacy system.
• breaking Given its age and abandonment, 'app' likely depends on extremely outdated versions of 'Connect' and other libraries, which may contain known security vulnerabilities and are not patched. Using it in production is a significant security risk.
  Fix: Do not use in production environments. Audit all transitive dependencies for vulnerabilities if used for legacy maintenance, or migrate to a secure, modern framework with active community support.
• gotcha The API is callback-based and does not natively support Promises or async/await, aligning with Node.js patterns from the early 2010s. Integrating it with modern asynchronous JavaScript can be challenging.
  Fix: Wrap callback-based functions in Promises manually using `util.promisify` or custom wrappers if integrating with modern async code, or consider rewriting routes using a contemporary framework.

Install

• npm install app npm
• yarn add app yarn
• pnpm add app pnpm

Imports

• App
  wrong:

  import { App } from 'app';
  import App from 'app';

  correct:

  const App = require('app');

  This package predates ES Modules and exclusively uses CommonJS `require()` syntax. The primary export is the `App` constructor.
• App Instance

  const app = new (require('app'))();

  A common pattern is to immediately instantiate the 'App' constructor after requiring it. This is not a distinct import but a usage pattern of the main export.
• Require for side effects (less common)
  wrong:

  import 'app';

  correct:

  require('app');

  While less common for frameworks, some CommonJS modules might be imported purely for side effects or to register globals. Using `import 'app'` for this purpose is incorrect for this CJS-only package.

Quickstart

Demonstrates the basic setup, defines a simple route for the root path, and starts the HTTP server to respond with 'Hello World'.

const App = require('app');
const app = new App();

// Define a route for the root path
app.routes({
  '': function (req, res, next){
    res.send('Hello World');
  }
});

// Start the server on port 3000
const PORT = process.env.PORT ?? 3000;
app.listen(PORT, () => {
  console.log(`App listening on http://localhost:${PORT}`);
  console.log('Open your browser to see "Hello World"');
});