Nodejs custom middlewares #nodejs

server.js

// Middlewares created while learning nodejs/express

const express = require('express');
const fs = require('fs');
const path = require('path');

require('dotenv').config();

const app = express();

// Custom middlewares:

// Middleware that logs hello in console
const helloMiddleWare = (req, res, next) => {
  res.send('hello');
  next();
};

// Middleware that does the same as app.get
const customGet = (relPath, handler) => {
  return (req, res, next) => {
    if (req.method === 'GET' && req.path === relPath) {
      handler(req, res, next);
    } else {
      next();
    }
  };
};

// Middleware that does the same as express.static middleware;
const customStatic = folderPath => {
  return (req, res, next) => {
    if (req.method === 'GET') {
      const fullPath = path.join(folderPath, req.path);
      if (fs.existsSync(fullPath)) return res.sendFile(path.resolve(fullPath));
    }
    return next();
  };
};

// Middleware that proxies any request whose path starts with '/api' to another url
const customProxy = (req, res, next) => {
  if (/^\/api\//.test(req.path)) {
    const newUrl = `${baseUrl}${req.path.slice(5)}`;

    const options = {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(req.body)
    };

    return fetch(newUrl, options)
      .then(proxyRes => proxyRes.json())
      .then(proxyRes => {
        res.json(proxyRes);
      })
      .catch(err => {
        res.status(500).send();
      });
  }
  return next();
};

// Routes:

app.use(customProxy);

app.use(customStatic('static'));

app.use(customGet('/', (req, res) => {
  res.sendFile('index.html');
}))

// Listen to port:
const listener = app.listen(3000, () => {
  console.log(`Your app is listening on port ${listener.address().port}`);
});