Dropzone.js is a light weight JavaScript library that turns an HTML element into a dropzone. This means that a user can drag and drop a file onto it, and the file gets uploaded to the server via AJAX.

If you want support, please use stackoverflow with the dropzone.js tag and not the GitLab issues tracker. Only post an issue here if you think you discovered a bug or have a feature request.

Please read the contributing guidelines before you start working on Dropzone!

Dropzone does not depend on jQuery.

Dropzone is compatible with bower, there's a standalone version of Dropzone, an AMD module that's compatible with RequireJS in the downloads folder.

Main features

• Image thumbnail previews. Simply register the callback thumbnail(file, data) and display the image wherever you like
• Retina enabled
• Multiple files and synchronous uploads
• Progress updates
• Support for large files
• Complete theming. The look and feel of Dropzone is just the default theme. You can define everything yourself by overwriting the default event listeners.
• Browser image resizing (resize the images before you upload them to your server)
• Well tested

Documentation

For the full documentation and installation please visit www.dropzonejs.com

Please also refer to the FAQ.

Examples

For examples, please see the GitLab wiki.

Installation

You probably only need to look at the simple example (source) to get started. Continue reading for step by step instructions and different installation approaches.

Download the standalone dropzone.js and include it like this:

<script src="./path/to/dropzone.js"></script>

Dropzone is now activated and available as window.Dropzone.

Dropzone does not handle your file uploads on the server. You have to implement the code to receive and store the file yourself. See the section Server side implementation for more information.

This is all you need to get dropzone up and running, but if you want it to look like the dropzone on this page, you’ll need to use the dropzone.css in the dist folder.

With RequireJS

Dropzone is also available as an AMD module for RequireJS.

You can find the dropzone-amd-module in the dist folder.

Usage

The typical way of using dropzone is by creating a form element with the class dropzone:

<form action="/file-upload"
      class="dropzone"
      id="my-awesome-dropzone"></form>

That’s it. Dropzone will find all form elements with the class dropzone, automatically attach itself to it, and upload files dropped into it to the specified action attribute. The uploaded files can be handled just as if there would have been a html input like this:

<input type="file" name="file" />

If you want another name than file you can configure dropzone with the option paramName.

If you want your file uploads to work even without JavaScript, you can include an element with the class fallback that dropzone will remove if the browser is supported. If the browser isn’t supported, Dropzone will not create fallback elements if there is a fallback element already provided. (Obviously, if the browser doesn’t support JavaScript, the form will stay as is)

Typically this will look like this:

<form action="/file-upload" class="dropzone">
  <div class="fallback">
    <input name="file" type="file" multiple />
  </div>
</form>

Create dropzones programmatically

Alternatively you can create dropzones programmaticaly (even on non form elements) by instantiating the Dropzone class

// Dropzone class:
var myDropzone = new Dropzone("div#myId", { url: "/file/post"});

or if you use jQuery, you can use the jQuery plugin Dropzone ships with:

// jQuery
$("div#myId").dropzone({ url: "/file/post" });

Don’t forget to specify an url option if you’re not using a form element, since Dropzone doesn’t know where to post to without an action attribute.

Server side implementation

Dropzone does not provide the server side implementation of handling the files, but the way files are uploaded is identical to simple file upload forms like this:

<form action="" method="post" enctype="multipart/form-data">
  <input type="file" name="file" />
</form>

To handle basic file uploads on the server, please look at the corresponding documentation. Here are a few documentations, if you think I should add some, please contact me.

• AngularJS and Spring
• NodeJS with express
• Ruby on rails
• Complete PHP tutorial by startutorial.com
• Basic PHP file upload
• Tutorial for Dropzone and Lavarel (PHP) written by Maksim Surguy
• Symfony2 and Amazon S3
• File upload in ASP.NET MVC using Dropzone JS and HTML5
• Servicestack and Dropzone
• How to build a file upload form using DropzoneJS and Go
• How to display existing files on server using DropzoneJS and Go

Paid documentations:

• eBook for Dropzone with PHP by startutorial.com.

Please look at the Dropzone FAQ if you need more information.

Configuration

There are two ways to configure dropzones.

The obvious way is to pass an options object when instantiating a dropzone programmatically like in the previous create dropzones programmatically section.

But if you just have HTML elements with the dropzone class, then you don’t programmatically instantiate the objects, so you have to store the configuration somewhere so Dropzone knows how to configure the dropzones when instantiating them.

This is done with the Dropzone.options object.

// "myAwesomeDropzone" is the camelized version of the HTML element's ID
Dropzone.options.myAwesomeDropzone = {
  paramName: "file", // The name that will be used to transfer the file
  maxFilesize: 2, // MB
  accept: function(file, done) {
    if (file.name == "justinbieber.jpg") {
      done("Naha, you don't.");
    }
    else { done(); }
  }
};

If you want to disable the auto discover behaviour of Dropzone, you can either disable it on a per element basis, or in general:

// Prevent Dropzone from auto discovering this element:
Dropzone.options.myAwesomeDropzone = false;
// This is useful when you want to create the
// Dropzone programmatically later

// Disable auto discover for all elements:
Dropzone.autoDiscover = false;

List of configuration options

You can also overwrite all default event actions in the options. So if you provide the option drop you can overwrite the default drop event handler. You should be familiar with the code if you do that because you can easily break the upload like this. If you just want to do additional stuff, like adding a few classes here and there, listen to the events instead!

Enqueuing file uploads

When a file gets added to the dropzone, its status gets set to Dropzone.QUEUED (after the accept function check passes) which means that the file is now in the queue.

If you have the option autoProcessQueue set to true then the queue is immediately processed, after a file is dropped or an upload finished, by calling .processQueue() which checks how many files are currently uploading, and if it’s less than options.parallelUploads, .processFile(file) is called.

If you set autoProcessQueue to false, then .processQueue() is never called implicitly. This means that you have to call it yourself when you want to upload all files currently queued.

Layout

The HTML that is generated for each file by dropzone is defined with the option previewTemplate which defaults to this:

<div class="dz-preview dz-file-preview">
  <div class="dz-details">
    <div class="dz-filename"><span data-dz-name></span></div>
    <div class="dz-size" data-dz-size></div>
    <img data-dz-thumbnail />
  </div>
  <div class="dz-progress"><span class="dz-upload" data-dz-uploadprogress></span></div>
  <div class="dz-success-mark"><span>✔</span></div>
  <div class="dz-error-mark"><span>✘</span></div>
  <div class="dz-error-message"><span data-dz-errormessage></span></div>
</div>

The container (dz-preview) gets the dz-processing class when the file gets processed, dz-success when the file got uploaded and dz-error in case the file couldn’t be uploaded. In the latter case, data-dz-errormessage will contain the text returned by the server.

To overwrite the default template, use the previewTemplate config.

You can access the HTML of the file preview in any of the events with file.previewElement.

If you decide to rewrite the previewTemplate from scratch, you should put elements with the data-dz-* attributes inside:

• data-dz-name
• data-dz-size
• data-dz-thumbnail (This has to be an <img /> element and the alt and src attributes will be changed by Dropzone)
• data-dz-uploadprogress (Dropzone will change the style.width property from 0% to 100% whenever there’s a uploadprogress event)
• data-dz-errormessage

The default options for Dropzone will look for those element and update the content for it.

If you want some specific link to remove a file (instead of the built in addRemoveLinks config), you can simply insert elements in the template with the data-dz-remove attribute. Example:

<img src="removebutton.png" alt="Click me to remove the file." data-dz-remove />

You are not forced to use those conventions though. If you override all the default event listeners you can completely rebuild your layout from scratch.

See the installation section on how to add the stylesheet and spritemaps if you want your dropzone to look like the one on this page.

See the Theming section, for a more in depth look at how to change Dropzone’s UI.

I created an example where I made Dropzone look and feel exactly the way jQuery File Uploader does with a few lines of configuration code. Check it out!

Again, please look at the Dropzone FAQ if you’re still unclear about some features.

Dropzone methods

If you want to remove an added file from the dropzone, you can call .removeFile(file). This method also triggers the removedfile event.

Here’s an example that would automatically remove a file when it’s finished uploading:

myDropzone.on("complete", function(file) {
  myDropzone.removeFile(file);
});

If you want to remove all files, simply use .removeAllFiles(). Files that are in the process of being uploaded won’t be removed. If you want files that are currently uploading to be canceled, call .removeAllFiles(true) which will cancel the uploads.

If you have autoProcessQueue disabled, you’ll need to call .processQueue() yourself.

This can be useful if you want to display the files and let the user click an accept button to actually upload the file(s).

To access all files in the dropzone, use myDropzone.files.

To get

• all accepted files: .getAcceptedFiles()
• all rejected files: .getRejectedFiles()
• all queued files: .getQueuedFiles()
• all uploading files: .getUploadingFiles()

If you do not need a dropzone anymore, just call .disable() on the object. This will remove all event listeners on the element, and clear all file arrays. To reenable a Dropzone use .enable().

If you don’t like the default browser modals for confirm calls, you can handle them yourself by overwriting Dropzone.confirm.

Dropzone.confirm = function(question, accepted, rejected) {
  // Ask the question, and call accepted() or rejected() accordingly.
  // CAREFUL: rejected might not be defined. Do nothing in that case.
};

If you want Dropzone to display an image you have on your server, you can use:

// callback and crossOrigin are optional
let mockFile = { name: "Filename", size: 12345 };
myDropzone.displayExistingFile(mockFile, 'https://image-url');

See the FAQ on How to show files stored on server for more information.

Events

Dropzone triggers events when processing files, to which you can register easily, by calling .on(eventName, callbackFunction) on your instance.

Since listening to events can only be done on instances of Dropzone, the best place to setup your event listeners, is in the init function:

// The recommended way from within the init configuration:
Dropzone.options.myAwesomeDropzone = {
  init: function() {
    this.on("addedfile", function(file) { alert("Added file."); });
  }
};

If you create your Dropzones programmatically, you can setup your event listeners on your instances, like this:

// This example uses jQuery so it creates the Dropzone, only when the DOM has
// loaded.

// Disabling autoDiscover, otherwise Dropzone will try to attach twice.
Dropzone.autoDiscover = false;
// or disable for specific dropzone:
// Dropzone.options.myDropzone = false;

$(function() {
  // Now that the DOM is fully loaded, create the dropzone, and setup the
  // event listeners
  var myDropzone = new Dropzone("#my-dropzone");
  myDropzone.on("addedfile", function(file) {
    /* Maybe display some more file information on your page */
  });
})

This is a bit more complex, and not necessary unless you have a good reason to instantiate Dropzones programmatically.

Dropzone itself relies heavily on events. Everything that’s visual is created by listening to them. Those event listeners are setup in the default configuration of every Dropzone and can be overwritten, thus replacing the default behavior with your own event callback.

You should only do this when you really know how Dropzone works, and when you want to completely theme your Dropzone

List of events

Theming

If you want to theme your Dropzone to look fully customized, in most cases you can simply replace the preview HTML template, adapt your CSS, and maybe create a few additional event listeners.

You will go very far with this approach. As an example, I created an example where I made Dropzone look and feel exactly the way jQuery File Uploader does with a few lines of configuration code. Check it out!

As you can see, the biggest change is the previewTemplate. I then added a few additional event listeners to make it look exactly like the reference.

You can however, implement your UI completely from scratch.

Dropzone itself sets up a lot of event listeners when a Dropzone is created, that handle all your UI. They do stuff like: create a new HTML element, add the <img> element when provided with image data (with the thumbnail event), update the progress bar when the uploadprogress event fires, show a checkmark when the success event fires, etc...

Everything visual is done in those event handlers. If you would overwrite all of them with empty functions, Dropzone would still be fully functional, but wouldn’t display the dropped files anymore.

If you like the default look of Dropzone, but would just like to add a few bells and whistles here and there, you should just add additional event listeners instead.

Overwriting the default event listeners, and creating your own, custom Dropzone, would look something like this:

// This is an example of completely disabling Dropzone's default behavior.
// Do *not* use this unless you really know what you are doing.
Dropzone.myDropzone.options = {
  previewTemplate: document.querySelector('#template-container').innerHTML,
  // Specifing an event as an configuration option overwrites the default
  // `addedfile` event handler.
  addedfile: function(file) {
    file.previewElement = Dropzone.createElement(this.options.previewTemplate);
    // Now attach this new element some where in your page
  },
  thumbnail: function(file, dataUrl) {
    // Display the image in your file.previewElement
  },
  uploadprogress: function(file, progress, bytesSent) {
    // Display the progress
  }
  // etc...
};

Obviously this lacks the actual implementation. Look at the source to see how Dropzone does it internally.

You should use this option if you don’t need any of the default Dropzone UI, but are only interested in Dropzone for it’s event handlers, file upload and drag’n’drop functionality.

Tips

If you do not want the default message at all (»Drop files to upload (or click)«), you can put an element inside your dropzone element with the class dz-message and dropzone will not create the message for you.

Dropzone will submit any hidden fields you have in your dropzone form. So this is an easy way to submit additional data. You can also use the params option.

Dropzone adds data to the file object you can use when events fire. You can access file.width and file.height if it’s an image, as well as file.upload which is an object containing: progress (0-100), total (the total bytes) and bytesSent.

If you want to add additional data to the file upload that has to be specific for each file, you can register for the sending event:

myDropzone.on("sending", function(file, xhr, formData) {
  // Will send the filesize along with the file as POST data.
  formData.append("filesize", file.size);
});

To access the preview html of a file, you can access file.previewElement. For example:

myDropzone.on("addedfile", function(file) {
  file.previewElement.addEventListener("click", function() {
    myDropzone.removeFile(file);
  });
});

If you want the whole body to be a Dropzone and display the files somewhere else you can simply instantiate a Dropzone object for the body, and define the previewsContainer option. The previewsContainer should have the dropzone-previews or dropzone class to properly display the file previews.

new Dropzone(document.body, {
  previewsContainer: ".dropzone-previews",
  // You probably don't want the whole body
  // to be clickable to select files
  clickable: false
});

Look at the gitlab wiki for more examples.

If you have any problems using Dropzone, please try to find help on stackoverflow.com by using the dropzone.js tag. Only create an issue on GitLab when you think you found a bug or want to suggest a new feature.

Compatibility

This section describes compatibility with browsers and older versions of Dropzone.

Browser Support

• Chrome 7+
• Firefox 4+
• IE 10+
• Opera 12+ (Version 12 for MacOS is disabled because their API is buggy)
• Safari 6+

For all the other browsers, dropzone provides an oldschool file input fallback.

There is no workaround for drag’n’drop in older browsers – it simply isn't supported. The same goes for image previews, etc... But using dropzone, your users using an old browser will be able to upload files. It just won’t look and feel great. But hey, that’s their fault.

Version 5.0

• Starting with version 5.2, dropzone is no longer written in CoffeeScript, but in EcmaScript6. To still work in older browsers, the code is still compiled with babel.

Version 4.0

• Changed the default previewTemplate. Check out the new one in the layout section.
• Using an already included SVG instead of a PNG spritemap (the CSS file is now the only additional file that you need to include)

Version 3.0

• All classes are prefixed with dz- now to prevent clashing with other CSS definitions
• The way previewTemplate is defined has changed. You have to provide data-dz-* elements now
• If the server returns JSON, it will be parsed for error messages as well
• There’s a dict* option for all of the visible messages
• Lots of minor fixes and changes

Version 2.0

Starting with version 2.0, Dropzone no longer depends on jQuery, but Dropzone still registers itself as a jQuery module if available.

That means that creating your Dropzones like this still works:

$("#my-dropzone").dropzone({ /* options */ });

If you create your Dropzones with the normal constructor though, you have to pass either the raw HTMLElement, or a selector string. So those versions all work:

// With jQuery
new Dropzone($("#my-dropzone").get(0));
// Without jQuery
new Dropzone("#my-dropzone");
new Dropzone(document.querySelector("#my-dropzone"));

Another thing that changed, is that Dropzone no longer stores its instances inside the element’s data property. So to get a dropzone for an element do this now:

// DEPRECATED, do not use:
$("#my-dropzone").data("dropzone"); // won't work anymore
// Do this now:
Dropzone.forElement(element); // Providing a raw HTMLElement
// or
Dropzone.forElement("#my-dropzone"); // Providing a selector string.

Why another library?

I realize that there are already other libraries out there but the reason I decided to write my own are the following:

• I didn't want it to be too big, and to cumbersome to dive into.
• I want to design my own elements. I only want to register callbacks so I can update my elements accordingly.
• Big files should get uploaded without a problem.
• I wanted a callback for image previews, that don't kill the browser if too many too big images are viewed.
• I want to use the latest API of browsers. I don't care if it falls back to the normal upload form if the browser is too old.
• I don't think that it's necessary anymore to depend on libraries such as jQuery (especially when providing functionality that isn't available in old browsers anyway).

MIT License

See LICENSE file