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Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

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Use npm Packages

We can make npm packages available for you to use in your JavaScript. We use webpack to prepare them and make them available to import. We'll also process your JavaScript with Babel.

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HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

              <div id="drop-area">
  <form class="my-form">
    <p>Upload multiple files with the file dialog or by dragging and dropping images onto the dashed region</p>
    <input type="file" id="fileElem" multiple accept="image/*" onchange="handleFiles(this.files)">
    <label class="button" for="fileElem">Select some files</label>
  <progress id="progress-bar" max=100 value=0></progress>
  <div id="gallery" /></div>
<div class="note"><strong>Note: I've Removed the ability to actually upload files (it will error out silently since there is no error handler, so it'll still appear to work) because you guys were constantly filling up my Cloudinary account. Please <a href="">create your own account</a> and replace the "joezim007" and "ujpu6gyk" bits in the JavaScript with your own account's information.</strong></div>
              body {
  font-family: sans-serif;
a {
  color: #369;
.note {
  width: 500px;
  margin: 50px auto;
  font-size: 1.1em;
  color: #333;
  text-align: justify;
#drop-area {
  border: 2px dashed #ccc;
  border-radius: 20px;
  width: 480px;
  margin: 50px auto;
  padding: 20px;
#drop-area.highlight {
  border-color: purple;
p {
  margin-top: 0;
.my-form {
  margin-bottom: 10px;
#gallery {
  margin-top: 10px;
#gallery img {
  width: 150px;
  margin-bottom: 10px;
  margin-right: 10px;
  vertical-align: middle;
.button {
  display: inline-block;
  padding: 10px;
  background: #ccc;
  cursor: pointer;
  border-radius: 5px;
  border: 1px solid #ccc;
.button:hover {
  background: #ddd;
#fileElem {
  display: none;
              // ************************ Drag and drop ***************** //
let dropArea = document.getElementById("drop-area")

// Prevent default drag behaviors
;['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
  dropArea.addEventListener(eventName, preventDefaults, false)   
  document.body.addEventListener(eventName, preventDefaults, false)

// Highlight drop area when item is dragged over it
;['dragenter', 'dragover'].forEach(eventName => {
  dropArea.addEventListener(eventName, highlight, false)

;['dragleave', 'drop'].forEach(eventName => {
  dropArea.addEventListener(eventName, unhighlight, false)

// Handle dropped files
dropArea.addEventListener('drop', handleDrop, false)

function preventDefaults (e) {

function highlight(e) {

function unhighlight(e) {

function handleDrop(e) {
  var dt = e.dataTransfer
  var files = dt.files


let uploadProgress = []
let progressBar = document.getElementById('progress-bar')

function initializeProgress(numFiles) {
  progressBar.value = 0
  uploadProgress = []

  for(let i = numFiles; i > 0; i--) {

function updateProgress(fileNumber, percent) {
  uploadProgress[fileNumber] = percent
  let total = uploadProgress.reduce((tot, curr) => tot + curr, 0) / uploadProgress.length
  console.debug('update', fileNumber, percent, total)
  progressBar.value = total

function handleFiles(files) {
  files = [...files]

function previewFile(file) {
  let reader = new FileReader()
  reader.onloadend = function() {
    let img = document.createElement('img')
    img.src = reader.result

function uploadFile(file, i) {
  var url = ''
  var xhr = new XMLHttpRequest()
  var formData = new FormData()'POST', url, true)
  xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest')

  // Update progress (can be used to show progress indicator)
  xhr.upload.addEventListener("progress", function(e) {
    updateProgress(i, (e.loaded * 100.0 / || 100)

  xhr.addEventListener('readystatechange', function(e) {
    if (xhr.readyState == 4 && xhr.status == 200) {
      updateProgress(i, 100) // <- Add this
    else if (xhr.readyState == 4 && xhr.status != 200) {
      // Error. Inform the user

  formData.append('upload_preset', 'ujpu6gyk')
  formData.append('file', file)
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