express sample code for uploading files

index.js

const express = require('express');
const bodyParser = require('body-parser');
const app = express();
const crypto = require('crypto');
const multer = require('multer');
const upload = multer();

app.use(bodyParser.urlencoded({ extended: true }));
// app.use(express.urlencoded());  // deprecated

app.get('/', (req, res) => {
    res.send(`
    POST:
        <form method="POST" action="/post">
        <input type="text" name="fieldName" value="name">
        <input type="file" name="uploadFile">
        <input type="file" name="uploadFile2">
        <input type="submit">
        </form>
    POST form-urlencoded:
        <form method="POST" action="/urlencoded" enctype="application/x-www-form-urlencoded">
        <input type="text" name="fieldName" value="name">
        <input type="file" name="uploadFile">
        <input type="file" name="uploadFile2">
        <input type="submit">
        </form>
    POST form-data:
        <form method="POST" action="/formdata" enctype="multipart/form-data">
        <input type="text" name="fieldName" value="name">
        <input type="file" name="uploadFile">
        <input type="file" name="uploadFile2">
        <input type="submit">
        </form>
    PUT file:
        <form class="put-form">
        <input type="file" name="uploadFile" multiple>
        <input type="submit">
        </form>
    <script src="postForm.js"></script>
    `);
});

// script for put form
// https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Sending_and_Receiving_Binary_Data
app.get('/postForm.js', function (req, res) {
    res.type('text/javascript').send(`
        var putForm = document.querySelector('form.put-form')
        putForm.addEventListener('submit', submitPutForm)
        function submitPutForm(e) {
            e.preventDefault()
            var files = e.target.elements[0].files;
            for (var i = 0 ; i < files.length ; ++ i) {
                openFile(files[i],
                    function (err, file) {
                        if (err) return console.error(err)
                        putBlob(file.name, file.data,
                            function (err, rsp) {
                                if (err) return console.error(err)
                                appendText(rsp);
                            }
                        )
                    }
                )
            }
            e.target.reset();
        }
        function appendText(text, root) {
            if (!root) root = document.body
            var p = document.createElement('p')
            p.textContent = text
            root.appendChild(p)
        }
        function openFile(file, cb) {
            var r = new FileReader()
            r.onload = function () { cb(null, {name: file.name, data: r.result}) }
            r.onerror = function (error) { cb(error) }
            r.readAsArrayBuffer(file)
        }
        function putBlob(name, blob, cb) {
            var r = new XMLHttpRequest()
            r.onerror = function (err) { cb(err) }
            r.open("PUT", "/put/" + name)
            r.onreadystatechange = function () {
              if (r.readyState != 4) return
              if (r.status != 200) return cb('response status != 200,' + r.status)
              cb(null, r.responseText)
            }
            r.send(blob)
        }
    `);
});

// the default post is urlencoded
app.post('/post', function (req, res) {
    res.send(req.path + JSON.stringify(req.body));
});

// curl -d fieldName=name -d uploadFile="Screenshot from 2021-09-30 14-45-46.png" http://localhost:3000/urlencoded
app.post('/urlencoded', function (req, res) {
    res.send(req.path + JSON.stringify(req.body));
});

function getInfoFromData(name, data) {
    return {
        name: name,
        size: data.length,
        md5: crypto.createHash('md5').update(data).digest('hex'),
        sha1: crypto.createHash('sha1').update(data).digest('hex'),
        sha256: crypto.createHash('sha256').update(data).digest('hex'),
    }
}

// curl -F fieldName=name -F uploadFile=@"Screenshot from 2021-09-30 14-45-46.png" http://localhost:3000/formdata
app.post('/formdata', upload.any(), function (req, res) {
    res.send(req.path +
        JSON.stringify(req.body) +
        JSON.stringify(req.files.map(f => getInfoFromData(f.originalname, f.buffer)))
    );
});

// curl -T "Screenshot from 2021-09-30 14-45-46.png" http://localhost:3000/put/
// https://nodejs.dev/learn/get-http-request-body-data-using-nodejs
app.put('/put/:filename', async function (req, res) {
    let filename = req.params.filename;
    let buffers = [];
    for await (const chunk of req) buffers.push(chunk);
    let data = Buffer.concat(buffers);
    res.send(req.path + JSON.stringify(getInfoFromData(filename, data)));
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log('Port:', PORT));

package.json

{
  "scripts": {
    "start": "node index.js"
  },
  "dependencies": {
    "body-parser": "^1.19.0",
    "crypto": "^1.0.1",
    "express": "^4.17.1",
    "multer": "^1.4.3"
  }
}