Express.JS Upload Single File Example

Below is the module to upload single file to server using express.js

var express = require('express')

var route1 = express.Router()

var multer = require('multer') // required package to read multipart from data

var upload = multer({
    dest: "./files"
}) // we can get more control using storage option (filename, destination functions supported)

route1.use('/', express.static(__dirname + '/files')); // not necessary to upload only. but necessary to server files

// below is post handler. multer supports three type of uploads := single, array, fields
// in the following post handler we are using single method of multer object which searches
// for 'filename' input.
route1.post('/', upload.single('filename'), function(req, res, next) { // next is not necessary . But you may want further processing
    res.send("done");
})

route1.get('*', function(req, res) { // serve upload page when get request is sent
    res.render("upload"); // template to render
})


module.exports = route1

How to Use:

1. Create a main.js file (main in you package.json file)
2. Insert following code

var express = require('express')

var app = express()

var route = require('./uploader.js') // uploader.js contains above module

app.use('/upload', route) // define the url of upload.js route

app.set('view engine', 'pug') // view rendering engine. 

app.set('views', './views') // folder containing .pug files for rendering

app.listen(80);

3. Now create a template file in your views folder with name ‘upload.pug’. For more on pug visit https://pugjs.org/api/getting-started.html

doctype html
html
	head
		title Upload
	body
		form(name='FormName', enctype='multipart/form-data', action='/upload', method='post')
			input(type='file', name='filename')
			input(type='submit')

Your file will be stored under directory files with random name and without any extension. To give a specific name and filter the type of files allowed use storage option in multer upload object creation.