full_app.js

// Include the express module into the poject for creating the server
const express = require("express")

// Include the multer module into the project for accepting files
const multer = require("multer")

// We will set the object received from the express() function to a variable "app"
const app = express()

// Set a port on which the server will run on
const port = 3000

const upload = multer({
	storage: multer.diskstorage({
		destination: "/upload/images",  // Storage location
		filename: (req, res, (cb) => {
			cb(null, Date.now() + path.extname(file.originalname)) // return a unique file name for every file				
		})
	}),
	
	limits: {fileSize: 20000000,   // This limits file size to 2 million bytes(2mb)
		 
	fileFilter: (req, file, cb) => {
		const validFileTypes = /jpg|jpeg|png/ // Create regex to match jpg and png
		
		// Do the regex match to check if file extenxion match
		const extname = validFileTypes.test(path.extname(file.originalname).toLowerCase())
		
		if(extname === true){
			// Return true and file is saved
			 return cb(null, true)
		}else{
			// Return error message if file extension does not match
			 cb("Error: Images Only!")
			}
		}
})
  
app.post("/upload", (req, res) => {
	// This is the response sent to the user in the browser once the file recieved
	upload(req, res, (err) => {
		if(err){
			res.send(err)
			// This will display the error message to the user
		}
		else{
			res.send("File Uploaded Successfully")
		// This shows the file has beem successfully uploaded
		// The image will be found in the public folder
			}
	})
})

// Create the server and let it run on the port 3001
app.listen(port, () => {
	console.log(`Server is running on port ${port}`)
})