How to handle file upload in Expressjs

Step 1: Initiate the project

mkdir uploader && cd uploadernpm init -y

The first line creates an empty directory and moves into it. A new NodeJS project is initiated in this directory.

A package.json file is created with the default details.

The package.json file should look just like this:

{  "name": "uploader",  "version": "1.0.0",  "description": "",  "main": "index.js",  "directories": {    "test": "test"  },  "scripts": {    "test": "echo \"Error: no test specified\" && exit 1"  },  "keywords": [],  "author": "",  "license": "ISC"}

This configuration takes the name from the folder name. It also assumes that we have an index.js file as our main file.

Step 2: Create an ExpressJS server

Create a new index.js file and put the following code in it:

// Import dependenciesconst express = require('express')const app = express()var bodyParser = require('body-parser')// Set portconst port = 3000// Register middlewaresapp.use(bodyParser.urlencoded({ extended: false }))// Home routeapp.get('/', (req, res) => {  res.send('Hello World!')})// Start listeningapp.listen(port, () => {  console.log(`Example app listening at http://localhost:＄{port}`)})

This file is our main application file. It requires a few dependencies that can be installed using:

npm i body-parser expressnpm i -D nodemon

The first dependency, body-parser, is a middleware that adds the request data to the request. The dev dependency nodemon restarts the server whenever a change is made to the code, which ensures that the server is always running.

Now you have a new ExpressJS server ready to go. Run the server using nodemon.

nodemon index.js

Now the server is active and can listen for requests.

You can test by visiting http://localhost:3000 on your browser.

Step 3: Create a form view

Next, to handle file upload, a file has to be uploaded. To upload a file, an HTML form can be used.

Create an index.html file in the directory, at the same level as our main file, index.js, and add in the following content: