added code examples

node/express/getting-started/README.md

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+# Related Blog Posts
+
+* [Getting Started with Express](https://reflectoring.io/getting-started-with-express/)

node/express/getting-started/errormiddleware.js

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+// errormiddleware.js
+const errorLogger = (err, req, res, next) => {
+    console.log( `error ${err.message}`) 
+    next(err) // calling next middleware
+  }
+  
+  const errorResponder = (err, req, res, next) => {
+    res.header("Content-Type", 'application/json')
+    
+    res.status(err.statusCode).send(err.message)
+  }
+  const invalidPathHandler = (req, res, next) => {
+    res.status(400)
+    res.send('invalid path')
+  }
+  
+module.exports = { errorLogger, errorResponder, invalidPathHandler }
+

node/express/getting-started/index.js

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+const express = require('express');
+
+const app = express();
+
+const requestLogger = (req, res, next) => {
+  console.log(req);
+  next();
+};
+
+const requireJsonContent = (req, res, next) => {
+  if (req.headers['content-type'] !== 'application/json') {
+      res.status(400).send('Server requires application/json')
+  } else {
+    next()
+  }
+}
+
+app.use(requestLogger);
+
+const myErrorHandler = (err, req, res, next) => {
+                            if (req.foo) {
+                              res.status(500).send('Fail!');
+                            }else {
+                              next(err);
+                            }
+                          };
+
+app.use(myErrorHandler);
+app.use((err, req, res, next) => {
+  res.status(500).send('Error!')
+})
+
+// Set the body size limit to 100 bytes
+app.use(express.json({ limit: 100 }));
+
+app.use(express.urlencoded({ extended: false }));
+
+let products = [{"name":"television", "price":112.34, "brand":"samsung"},
+{"name":"washing machine", "price": 345.34, "brand": "LG"},
+{"name":"Macbook", "price": 3454.34, "brand": "Apple"}];
+
+
+// handle get request for path /
+app.get('/', (req, res) => {
+  res.send('response for GET request');
+});
+
+// handle get request for path /products
+app.get('/products', (req, res) => {
+
+  res.json(products);
+});
+
+// handle get request for path /products
+app.get('/products/:brand', (req, res) => {
+
+  const brand = req.params.brand;
+
+  console.log("brand ${brand} " + brand);
+  
+  const productsFiltered = products.filter(product=> product.brand == brand);                  
+
+  res.json(productsFiltered);
+});
+
+// handle post request for path /products
+app.post('/products', requireJsonContent, (req, res) => {
+  const products = [];
+
+  const name = req.body.name  ;                
+
+  const brand = req.body.brand;
+
+  console.log(name + " " + brand);
+  
+  products.push({name: req.body.name, brand: req.body.brand, price: req.body.price});               
+ 
+  const productCreationResponse = {productID: "12345", result: "success"};
+  res.json(productCreationResponse);
+});
+
+app.set('view engine', 'pug')
+app.set('views', './views')
+app.get('/home',  (req, res) => {
+  res.render("home", { title: "Home", message: "My home page" , sysdate: new Date().toLocaleString()})
+})
+
+
+// handle get request with 3 middleware functions
+app.get('/users', (req, res, next) => {
+  console.log("Stage 1 processing ");
+  next()
+},
+(req, res, next) => {
+  console.log("Stage 2 processing ");
+  next();
+},
+(req, res) => {
+  res.send('response for GET request');
+});
+
+
+app.get('/products/error', (req, res) => {
+  throw new Error("processing error!")
+});
+// start the server
+const port = 3000
+app.listen(3000, 
+   () => console.log(`Server listening on port ${port}.`));
+

node/express/getting-started/middleware.js

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+// middleware.js
+
+const requestLogger = (req, res, next) => {
+    console.log(req);
+    next();
+};
+  
+const requireJsonContent = (req, res, next) => {
+    if (req.headers['content-type'] !== 'application/json') {
+        res.status(400).send('Server requires application/json')
+    } else {
+      next()
+    }
+}
+
+module.exports = { requestLogger, requireJsonContent}

node/express/getting-started/package.json

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+{
+  "name": "storefront",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "express": "^4.17.2",
+    "pug": "^3.0.2"
+  }
+}

node/express/getting-started/routes.js

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+// routes.js
+const express = require('express')
+const { requireJsonContent } = require('./middleware')
+
+const router = express.Router()
+
+// Set the body size limit to 100 bytes
+router.use(express.json({ limit: 100 }))
+
+let  products = [{"name":"television", "price":112.34, "brand":"samsung"},
+{"name":"washing machine", "price": 345.34, "brand": "LG"},
+{"name":"Macbook", "price": 3454.34, "brand": "Apple"}];
+
+// handle get request for path /products
+router.get('/products', (req, res) => {
+  res.json(products);
+});
+
+// handle get request for path /products
+router.get('/products/:brand', (req, res) => {
+
+  const brand = req.params.brand;
+
+  console.log(`brand ${brand} `);
+  
+  const productsFiltered = products.filter(product=> product.brand == brand);                  
+
+  res.json(productsFiltered);
+});
+
+
+// handle post request for path /products
+router.post('/products', requireJsonContent,(req, res) => {
+
+  const name = req.body.name  ;                
+
+  const brand = req.body.brand;
+
+  console.log(name + " " + brand);
+  
+  products.push({name: req.body.name, brand: req.body.brand, price: req.body.price});               
+ 
+  const productCreationResponse = {productID: "12345", result: "success"};
+  res.json(productCreationResponse);
+});
+
+// handle put request for path /products
+router.put('/products', (req, res) => {
+
+  const name = req.body.name  ;                
+
+  const brand = req.body.brand;
+
+  console.log(name + " " + brand);
+  
+  products.push({name: req.body.name, brand: req.body.brand, price: req.body.price});               
+ 
+  const productCreationResponse = {productID: "12345", result: "success"};
+  res.json(productCreationResponse);
+})
+
+router.get('/home',  (req, res) => {
+  console.log("rendering...")
+  res.render("home", { title: "Home", message: "My home page" , sysdate: new Date().toLocaleString()})
+})
+
+router.get('/productswitherror', (req, res) => {
+  let err = new Error("processing error ")
+  err.statusCode = 400
+  throw err
+});
+
+
+module.exports = router

node/express/getting-started/server.js

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+// server.js
+const express = require('express')
+const routes = require('./routes')
+
+const { requestLogger } = require('./middleware')
+const { errorLogger, errorResponder, invalidPathHandler } = require('./errormiddleware')
+
+
+const app = express()
+const PORT = process.env.PORT || 3000
+
+app.use(requestLogger)
+app.use(routes)
+
+app.use(errorLogger)
+app.use(errorResponder)
+app.use(invalidPathHandler)
+
+app.set('view engine', 'pug')
+app.set('views', './views')
+
+
+app.listen(PORT, () => {
+console.log(`Server listening at http://localhost:${PORT}`)
+})

node/express/getting-started/views/home.pug

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+html
+  head
+    title= title
+  body
+    h1= message
+    div
+      p Generated by express at 
+        span= sysdate