File Uploader

  • This is for the version 3.x of the widget. If you’re looking for the widget v2 docs, check here
  • Here’s how you migrate from v2 to v3.

Uploadcare File Uploader is an ultimate HTML5 File Uploader; it’s responsive and mobile-ready. The File Uploader is provided as a typical JavaScript library, has a tab-based UI, and provides an intuitive UX flow based on tabbed navigation.

Technically, File Uploader replaces your basic <input type="file"> controls which then become buttons that activate the File Uploader dialog. Click the button below and check out the File Uploader version 3.0 in action:

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File Uploader Features

Implementing File Uploader helps you perform the following tasks:

  • Uploads
    • Add file uploading capabilities to your website or app.
    • Upload files of any type and up to 5TB in size.
    • Get files from various upload sources including local storage, camera, social media, and cloud storage services.
    • Upload multiple files in one go.
    • Track how uploads are going via an individual progress bar for every file.
    • Enable Drag’n’Drop for your upload user experience.
    • Receive upload notifications.
    • Implement a CDN for uploading files faster.
  • Image Handling
  • Validation
    • Validate files by their format or size.
    • Control inbound image resolutions.
  • Security
    • Make your uploading system compatible with SOC2, HIPAA, and more.
  • Reliability
    • Make 99.9% percent of your uploads hit their target.
    • All of your uploads go to the storage covered by SLA and 99.9% uptime.

Supported Browsers

We support modern browsers including Internet Explorer (10 and later), Edge, Firefox, Google Chrome, Safari, and Opera. It's recommended to update to the most recent verison. We provide support for at least two recent versions of each browser. More on the browser versions support.

The File Uploader will most probably run in older browser versions as well, except for Internet Explorer < 10.

If you need legacy browsers support including IE8, check out Uploadcare Widget v2.

Install

If you’re up to installing Uploadcare File Uploader manually, feel free to choose either option:

Please refer to integrations for ready-made solutions for some platforms.

Before proceeding with your install, check out the dependencies and existing types of File Uploader bundles.

Dependencies

Uploadcare File Uploader does not have any external dependencies except for jQuery. We provide two different File Uploader versions: with built-in jQuery and without it. See the types of existing File Uploader bundles for more info.

For instance, with the jQuery-enabled widget version you could go like:

var $ = uploadcare.jQuery;
$('body').append('It works!');

Bundles

There are a few types of js bundles:

  • uploadcare.full.js — a full bundle with built-in jQuery,
  • uploadcare.js — a bundle without built-in jQuery,
  • uploadcare.api.js — a bundle without UI of the File Uploader and built-in jQuery, JavaScript API only,
  • uploadcare.ie8.js — a full bundle with built-in jQuery 1.x for IE 8 support (widget v. 2.x and below),
  • uploadcare.lang.en.js — a bundle without built-in jQuery, en locale only.

Each bundle has its minified version. Just add .min before .js, e.g. uploadcare.min.js.

By default, uploadcare.min.js is exported to NPM and other package managers.

Install from CDN

Embed the File Uploader client library using the <script> element in the <head> section of each page where you’d like the File Uploader to show up. This CDN link, for instance, embeds the File Uploader version with built-in jQuery:

<script src="https://ucarecdn.com/libs/widget/3.x/uploadcare.full.min.js" charset="utf-8"></script>

You might also happen to already use jQuery on your page. In this case, consider loading the light File Uploader version without built-in jQuery:

<script src="https://code.jquery.com/jquery-3.4.1.min.js" charset="utf-8"></script>
<script src="https://ucarecdn.com/libs/widget/3.x/uploadcare.min.js" charset="utf-8"></script>

Once you are done setting your public key and choosing an appropriate bundle, look through your page <body> and see where you want the File Uploader button to appear. Place the following <input> element there and make sure not to miss the name attribute:

<input type="hidden" role="uploadcare-uploader" name="my_file" />

Install from NPM

npm install uploadcare-widget
import uploadcare from 'uploadcare-widget'

Configure

Uploadcare File Uploader is highly customizable through File Uploader options. Most of the options can be set in one of the ways listed below. You can also implement mixed settings, i.e., when having multiple File Uploaders; their general behavior can be set using global variables while some of them may run based on local attributes.

You can set File Uploader options in the following ways:

Note, the live config will also provide you with ready-made code snippets holding all the set options as local attributes.

Global variables

Globals are specified as global JavaScript variables in your <script> tag. For example:

<script>
  UPLOADCARE_PUBLIC_KEY = 'demopublickey';
  UPLOADCARE_LOCALE = 'ru';
</script>

Local attributes

Local options are specified in the target <input> tag as data-* attributes. For example:

<input type="hidden" role="uploadcare-uploader"
  data-public-key="demopublickey"
  data-images-only
/>

Settings object

Most of the File Uploader options can also be set within the settings object. See the JavaScript API reference for details. For example:

uploadcare.openDialog(null, {
  publicKey: 'demopublickey',
  imagesOnly: true,
  crop: '300x200'
});

Setting boolean options

All boolean options are set globally with their JavaScript boolean values.

UPLOADCARE_CLEARABLE = true;
UPLOADCARE_PREVIEW_STEP = false;

When setting boolean options locally in HTML tag attributes, any value is interpreted as true, even an empty one. However, when setting local options to false, the respective value should strictly be either "false" or "disabled".

Setting local options to true:

<input data-option="data-option" />
<input data-option="true" />
<input data-option="" />
<input data-option />

Setting local options to false:

<input data-option="false" />
<input data-option="disabled" />

Upload Sources

In many cases, local storage is not the best place to put your files. That is why Uploadcare implements over a dozen upload sources, so your users would not have to use their device storage if they aren’t keeping any files there.

Our file uploader, the Uploadcare File Uploader, uses the tabbed navigation to switch between upload sources. You can upload media from local and cloud storage, URLs, social media, and many more. The complete list follows.

In the File Uploader options, upload sources are controlled as separate tabs, and the set of enabled tabs is controlled via the data-tabs option.

The quickest way to play with the tab settings would be through File Uploader configurator. You can also share live config settings: the changes you implement will modify the configurator URL. This reference, for instance, navigates you to the File Uploader configured to use file, camera, and url upload sources only.

Available sources

Code

File Source

Default

file

Local disk

On

camera

Local webcam

On

url

Any URL

On

facebook

Facebook

On

gdrive

Google Drive

On

gphotos

Google Photos

On

dropbox

Dropbox

On

instagram

Instagram

On

evernote

Evernote

On

flickr

Flickr

On

onedrive

OneDrive

On

box

Box

Off

vk

VK

Off

huddle

Huddle

Off

Configuring Upload Sources

You can configure the set of upload sources globally or per File Uploader instance. The File Uploader option controlling the set of available sources globally is called UPLOADCARE_TABS; locally you can do it via the data-tabs attribute.

In both cases, you provide a string holding space-separated list of tab names you want to enable in the File Uploader UI.

Configuring the set of sources globally:

<script>
  UPLOADCARE_TABS = 'url file facebook';
</script>

Configuring the list of sources locally:

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-tabs="url file facebook"
/>

Custom Tabs

We get you might extend the File Uploader with functions specific to your product. That’s done by adding custom tabs to the File Uploader.

You start with registering a tab under some name and adding it to the list of your File Uploader tabs. Let’s cover the process of adding a new tab, the one listing files uploaded via your File Uploader instance:

Registering a New Tab

You register a new tab via the registerTab method.

<div id="uploader-placeholder">Uploading. Please wait...</div>
<script>
function favoriteFiles(container, button, dialogApi, settings) {
  ...
}
uploadcare.registerTab('favorites', favoriteFiles);
uploadcare.openPanel('#uploader-placeholder', null, {
  tabs: 'favorites file facebook dropbox gdrive instagram vk',
  favoriteFiles: [...]
});
</script>

Coding What the Tab Does

Once the tab is registered, we need to code its functionality. When making the tab listing file uploads made via some File Uploader instance, next step is passing a list of file UUIDs with the settings object. When a user selects a file for upload, its info can be passed to the dialog using dialogApi.

function favoriteFiles(container, button, dialogApi, settings) {
  $.each(settings.favoriteFiles, function(i, uuid) {
    container.append($('<img>', {
        'class': 'favorite-files-image',
        'src': settings.cdnBase + '/' + uuid + '/-/scale_crop/280x280/center/',
      })
      .on('click', function(e) {
        dialogApi.addFiles([uploadcare.fileFrom('uploaded', uuid, settings)])
      })
    );
  });
}

Adjusting the Tab Look

You can go beyond coding what the tab does to customizing ist look via CSS. In case you want to add custom icons, make use of the <svg> and <symbol> elements. Check out the example below:

<svg width="0" height="0" style="position:absolute">
  <symbol id="uploadcare--icon-favorites" viewBox="0 0 32 32">
    <path d="M 16 22.928 L 23.416 27.4 L 21.454 18.965 L 28 13.292 L 19.37 12.552 L 16 4.6 L 12.629 12.552 L 4 13.292 L 10.546 18.965 L 8.584 27.4 Z"/>
  </symbol>
</svg>
.uploadcare--menu__item_tab_favorites.uploadcare--menu__item_current {
  color: #f0cb3c;
}

Live Example

Here’s a live example of the File Uploader with the custom tab listing files uploaded via the specific File Uploader instance:

Multiple Files

Uploadcare File Uploader allows you to handle multiple files in one go and track progress via individual progress bars.

The multi-uploading behavior is enabled by adding the boolean data-multiple attribute set to true to your File Uploader <input> element, the one having its role specified as role="uploadcare-uploader".

<input type="hidden" role="uploadcare-uploader" name="my_files"
  data-multiple="true"
/>

Here is the live File Uploader with multiple file uploads enabled:

Loading...

Once many files are uploaded, they get stored as a file group. You then get a group_id instead of a file UUID in the value.

Client-side image resize

It is common that you don’t want hi-res original images uploaded to your Uploadcare account. Doing so is inefficient on both ends:

  • Sending large images over mobile networks can be expensive for your users.
  • Large images take up your account storage limit and delivering those increase your traffic.

To handle the issue, Uploadcare File Uploader implements client-side image optimization via the data-image-shrink option.

The option is passed into your File Uploader as a string holding your preferred resolution and, optionally, a JPEG quality of the resulting image. The preferred resolution you provide does not affect original image aspect ratio.

Image Shrink outputs to:

  • JPEG in case an input image has no transparency.
  • PNG in case an input image includes transparent pixels.

Here are some examples of values you can specify for data-image-shrink to control the feature:

  • 800x600, shrinks images to 0.48 megapixels with the default JPEG quality of 80%.
  • 1600x1600 95%, shrinks images to 2.5 megapixels with the JPEG quality set to 95%.

The resolution you set for optimized images should not exceed 5 megapixels. All EXIF info from your original images will be copied to the resized ones. The copied EXIF info includes image orientation, camera model, geolocation, and settings.

Input images will not be optimized in the following cases:

  • When a client browser does not support all the required APIs.
  • When images are uploaded from social media or URLs.
  • If the original resolution / target resolution ratio falls behind 2.0. For example, you can not shrink a 2560x1560px (4 MP) image to 1600x1600px (2.5 MP) while this works with a 2448x3264px (8 MP) original. The reason we implemented this limit is to preserve an optimal balance between a decline in quality and drop in file size.

Live Examples

Resize to 1024x1024px on a client

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-preview-step=""
  data-image-shrink="1024x1024"
/>
Loading...

Resize multiple files to 640x640px on a client

<input type="hidden" role="uploadcare-uploader" name="my_files"
  data-multiple=""
  data-image-shrink="640x480"
/>
Loading...

Localization

Uploadcare File Uploader is highly customizable and implements UI translations and custom pluralization rules. With ... locales, you can make your app instantly adapt to user languages.

There currently are: ar az ca cs da de el en es et fr he it ja ko lv nb nl pl pt ro ru sk sr sv tr uk vi zhTW zh

You can either set an existing locale or add a custom one along with its pluralization rules.

Adding a locale

There is a chance the locale you need is not available in the File Uploader yet. In the case, it is worth contributing a new one. That is done by forking the main File Uploader repo and adding a new localization file to this list.

Another option is overriding specific locale items by altering your global File Uploader configuration:

UPLOADCARE_LOCALE = 'en';
UPLOADCARE_LOCALE_TRANSLATIONS = {
  buttons: {
    cancel: 'Cancel',
    remove: 'Remove',
    choose: {
      files: {
        one: 'Choose a file',
        other: 'Pick files'
      },
      images: {
        one: 'Choose an image',
        other: 'Load images'
      }
    }
  }
};

Compare the structure above with the default English locale and you will notice we used the snippet above to override two items in the default localization.

If a string item is missing in a locale you selected, and there is no override for it, English is a fallback. In fact, the English locale usually contains the most extensive set of items for latest File Uploader versions.

Pluralization rules

Pluralization rules deal with enumerabilty, it is when something can be counted. File uploader locale items hold some quantitative values, and you might want to override how those work. In the English locale, for instance, you can find things like "1 file" and "3 files". Such behavior will require a special structure. You can find one of those under the file: key in the locale file.

Strings holding quantitative values are based on the output of a pluralization function. You pass an input number into a function, and it outputs a proper subkey related to your input.

function pluralize(number) {
  // do something
  return 'some_subkey';
}

There are two subkeys for the English localization: one and other. However, it can get more complex with other languages. For example, take a look at file: subkeys for the Russian locale. We use the %1 sequence to format numbers into pluralized strings.

Each locale we provide with the File Uploader is supplied with its Unicode-based pluralization rules. If you wish to override those, you can define a custom pluralization function and assign it to the UPLOADCARE_LOCALE_PLURALIZE variable.

The following setting makes the File Uploader use the message under the some subkey for input numbers from 2 to 10.

UPLOADCARE_LOCALE_TRANSLATIONS = {
  file: {
    one: 'Only one file! :(',
    some: 'Only %1 files. Upload more.',
    many: '%1 files!! That\'s a lot.'
  }
};
UPLOADCARE_LOCALE_PLURALIZE = function(n) {
  if (n === 1) return 'one';
  if (n > 1 && n <= 10) return 'some';
  return 'many';
};

Styling

Uploadcare File Uploader can be quickly integrated into your product. This is also the case with your user interface.

Scaling File Uploader Elements

The File Uploader is designed to organically inherit styles from your page: dialog elements get scaled in line with your font size. Check out the examples below:

Times New Roman, 12px:

Loading...

Courier New, 18px:

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Styling With CSS

The File Uploader is thoroughly annotated with CSS classes. It's your starting point into a deeper customization. You can find a class for every File Uploader item by inspecting its elements or sifting through the File Uploader source code.

The File Uploader dialog window look can be customized via the uploadcare--dialog class.

Changing Uploader Button Color

Changing the button color is one of the most common cases. It can be easily done with CSS:

Button Shadow

You can add shadow and experiment with fonts and colors in CSS to any extent:

Uploading Circle Color

You can display the file uploading progress. The fill color can be changed via the CSS color property, while border-color will work for your background.

Here, you can test the File Uploader with a customized uploading circle:

Custom Progress Bar

You can replace the built-in progress bar. To do that, you need to listen to the current File Uploader object and get it in the onChange callback. It will be a file object for regular File Uploaders or a group object for multiple File Uploaders. After that listen to the progress event and change your progress bar in according to a current uploadProgress.

The following installProgressBar function does all that. It receives the two arguments: File Uploader instance and progress bar DOM element. Everything else runs on CSS, animation included.

See the Pen Custom progress bar exampleby uploadcare (@uploadcare) on CodePen.

Uploaded Image Preview

The default File Uploader behavior is when a user selects an image, and its preview is shown in the upload dialog. You might want to embed this preview in your page somewhere around the File Uploader button. Such a preview could be more informative than simply displaying file names and sizes.

Note, you have full control over size and position of your embed, just use CSS.

Image preview for a multi-file File Uploader may look different:

You can change the displayed images or rearrange the existing oness; all changes will then be reflected in the thumbnail list.

File Uploader Embed

We get that user experience matters and provide a good number of File Uploader customization options that cover both File Uploader appearance and behavior.

The look of the File Uploader can be changed via CSS, and the live config is a great starting point for controlling your File Uploader behavior.

Another thing you can do is embedding the File Uploader in your page by switching from the File Uploader dialog to panel.

Embed File Uploader Using Panel

The default behavior is when the File Uploader dialog appears on pushing a button. This covers the rest of your page with a semi-transparent background. It is a good fit when you use the File Uploader to fill in a single form field out of many.

However, when the purpose of your page is getting user-generated content, there is a sense in showing the File Uploader on a page without any preceding clicks or taps. The thing is called panel.

<div id="uploader-placeholder">Uploading. Please wait...</div>
<script>uploadcare.openPanel('#uploader-placeholder');</script>

The snippet above replaces your DOM element with the uploadcare-placeholder id and puts it in place once a user selects a file. This can be used to show some indication of the uploading process, for instance. Also, unlike the dialog, File Uploader panel can be closed by simply selecting a file.

Panel Styling

Same as the File Uploader dialog, panel can be customized.

Here is an example of customizing your File Uploader embed. Say, you don’t like its look because of the sharp border. The appearance of your embed can be changed via CSS. It goes like this:

#uploader-styling {
  margin-top: 10px;
}
#uploader-styling .uploadcare--panel,
#uploader-styling .uploadcare--menu__item,
#uploader-styling .uploadcare--menu__items {
  background-color: transparent;
  border: 0;
}
#uploader-styling .uploadcare--panel {
  flex-direction: column;
}
#uploader-styling .uploadcare--menu {
  width: 100%;
  height: 60px;
  min-height: 60px;
}
#uploader-styling .uploadcare--menu__items {
  padding-right: 0;
  flex-direction: row;
}

Some dialog elements are rendered as iframes by Uploadcare servers, which does not let you customize CSS. However, we provide a set of specific methods to inject CSS into iframes.

Image crop

Cropping images is such a common task that we decided to implement it right in the File Uploader UI.

Uploadcare File Uploader features a good bunch of crop options including free crop. Adding the feature to your File Uploader instance is done through implementing the data-crop option. Keep in mind this will alter your File Uploader behavior and hence user experience: a new step gets added to the flow, that’s where users will be able to apply cropping.

This alters the usual File Uploader behavior. Now, after users select their images for uploading, they encounter a step where cropping can be applied.

How Cropping Works

Technically, image cropping works as post-processing via the Image Processing feature:

  • Original images go to an Uploadcare project associated with a Public Key set for your File Uploader instance.
  • Crop is applied as the crop image processing operation by injecting its URL directive into original URLs.
  • The File Uploader returns resulting CDN URLs with injected crop.

Configuring Crop

Crop options are put into the data-crop attribute as a string holding comma-separated crop presets. When you define several presets, users will be able to choose from the related crop options right in the UI.

Each crop preset is a combination of a size or ratio definition and an optional keyword:

  • "disabled", crop is disabled. Can’t be combined with other presets.
  • "" or "free", crop is enabled; users can freely select any crop area on their images.
  • "2:3", any area with the aspect ratio of 2:3 can be selected for cropping.
  • "300x200" — same as above, but if the selected area is greater than 300x200 pixels, the resulting image will be downscaled to fit the dimensions.
  • "300x200 upscale" — same as above, but even if the selected area is smaller, the resulting image gets upscaled to fit the dimensions.
  • "300x200 minimum" — users won’t be able to define an area smaller than 300x200 pixels. If an image we apply crop to is smaller than 300x200 pixels, it will be upscaled to fit the dimensions.

Crop examples

Free crop:

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-crop=""
/>
Loading...

Choosing from predefined aspect ratios:

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-crop="free, 16:9, 4:3, 5:4, 1:1"
/>
Loading...

Fixed aspect ratio:

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-crop="4:3"
/>
Loading...

Fixed size with upscaling:

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-crop="400x300 upscale"
/>
Loading...

Default files in Uploader dialog

Uploadcare File Uploader allows you to make specified files appear in the File Uploader dialog on open.

Specifying files that appear on File Uploader dialog open is implemented by adding the value attribute to your File Uploader <input> element. The attribute may either be empty or hold a file CDN URL or UUID.

If you set the value externally and trigger the DOM change event, it affects the File Uploader. For instance, setting it to a file UUID or a CDN URL will result in that file loaded into the File Uploader. You can do this for a live File Uploader or even before it loads.

Here’s how you do it:

<input type="hidden" role="uploadcare-uploader" name="my_file"
  data-public-key="232d896709883f79bfaf"
  value="https://ucarecdn.com/9dd2f080-cc52-442d-aa06-1d9eec7f40d1/"
/>
<!--
  Also valid:
  value="9dd2f080-cc52-442d-aa06-1d9eec7f40d1"
-->

You may also want to check out a live example:

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JS snippets and CSS tricks

In this cookbook part, you can find popular code examples and resolutions of common tasks when working with File Uploader. Less words, more code!

Get a CDN URL of an uploaded file

For a single-upload widget.

// get a widget reference
const widget = uploadcare.SingleWidget("[role=uploadcare-uploader]");

// listen to the "upload completed" event
widget.onUploadComplete(fileInfo => {
  // get a CDN URL from the file info
  console.log(fileInfo.cdnUrl);
});

Get CDN URLs of uploaded files

For a multi-upload widget.

// get a widget reference
const widget = uploadcare.MultipleWidget("[role=uploadcare-uploader]");

// listen to the "change" event
widget.onChange(function (group) {
  // get a list of file instances
  group.files().forEach(file => {
    // once each file is uploaded, get its CDN URL from the fileInfo object
    file.done(fileInfo => {
      console.log(fileInfo.cdnUrl);
    });
  });
});

Get a group CDN URL

For a multi-upload widget.

// get a widget reference
const widget = uploadcare.MultipleWidget("[role=uploadcare-uploader]");

// listen to the "upload completed" event
widget.onUploadComplete(groupInfo => {
  // get CDN URL from group information
  console.log(groupInfo.cdnUrl);
});

Get a CDN URL of an uploaded file/group

For a dialog window.

// create a new dialog object
const dialog = uploadcare.openDialog(null, '', {
  multiple: false // set to true for multi-file uploads
});

// get a file or group instance
dialog.done(res => {
  // once a file or group is uploaded, get its CDN URL
  res.promise().done(info => {
    console.log(info.cdnUrl);
  });
});

Get a camera-recorded video duration

// get widget reference
const widget = uploadcare.Widget("[role=uploadcare-uploader]");

let cameraRecDuration = null;
let recStart = null;
let recEnd = null;

// calculate webcam recording duration
document.body.addEventListener("click", e => {
  // user clicks "start recording"
  if (e.target.classList.contains("uploadcare--camera__button_type_start-record")) {
    recStart = new Date().getTime();
  }
  // user clicks "stop recording"
  if (e.target.classList.contains("uploadcare--camera__button_type_stop-record")) {
    recEnd = new Date().getTime();
    cameraRecDuration = (recEnd - recStart) / 1000;
    console.log("Duration: ", cameraRecDuration);
  }
});

Check if a file was added or removed

// get widget reference
const widget = uploadcare.Widget("[role=uploadcare-uploader]")
// get dialog object to access its API
widget.onDialogOpen(dialog => {
  // listen to "file added" event
  dialog.fileColl.onAdd.add(file => {
    console.log("File added", file)
  });
  // listen to "file removed" event
  dialog.fileColl.onRemove.add(file => {
    console.log("File removed", file)
  });
});

Get the upload source

// get widget reference
const widget = uploadcare.Widget("[role=uploadcare-uploader]");

// listen to the "upload completed" event
widget.onUploadComplete(fileInfo => {
  // get source details from file information
  console.log(fileInfo.sourceInfo.source);
});

Add an overlay to the crop

.uploadcare--jcrop-tracker::after{
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  left: 0;
  /* URL of the overlay image */
  background-image: url(<https://i.imgur.com/hSbF6v0.png>);
  background-size: cover;
  background-position: center;
}

.uploadcare--jcrop-tracker:first-of-type{
  opacity: 1 !important;
  background-color: transparent !important;
}
Adding an overlay
Adding an overlay

Get a selected crop preset

<input type="hidden" role="uploadcare-uploader" name="my_file" id="uploadcare-file" data-crop="2:3, 5:6, 16:9" />
let currentPreset = '2:3';

document.addEventListener('click', e => {
  // user clicks on a crop preset icon
  if (e.target.classList.contains('uploadcare--crop-sizes__item') || e.target.classList.contains('uploadcare--crop-sizes__icon')) {
    // get the caption of the preset selected
    currentPreset = document.querySelector('.uploadcare--crop-sizes__item_current').dataset.caption;
    console.log(currentPreset);
  }
});

Upload an image from Base64

// original base64 image
const b64data = "data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==";

// convert dataURI to a File object
function dataURLtoFile(dataurl, filename) {
  let arr = dataurl.split(','),
      mime = arr[0].match(/:(.*?);/)[1],
      bstr = atob(arr[1]),
      n = bstr.length,
      u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  return new File([u8arr], filename, {type:mime});
}

// convert a base64 image to a File object
const fileToUpload = dataURLtoFile(b64data, "image");

// upload the file to Uploadcare
let upload = uploadcare.fileFrom("object", fileToUpload);

upload.done(fileInfo => {
  console.log("File uploaded: ", fileInfo.cdnUrl);
});

Render the uploaded image preview

// get widget reference
const widget = uploadcare.Widget("[role=uploadcare-uploader]");

widget.onUploadComplete(fileInfo => {
  const preview = document.createElement("img");
  // create a preview of the uploaded image of 200px width
  preview.src = fileInfo.cdnUrl + "-/resize/200x/";
  // add the thumbnail to the page
  document.body.appendChild(preview);
});

Add custom names to crop presets

<input type="hidden" role="uploadcare-uploader" name="my_file" id="uploadcare-file" data-crop="free,1:1,2:3" />
.uploadcare--crop-sizes__item {
  overflow: visible;
}
.uploadcare--crop-sizes__item:nth-child(1)::after {
  content: "Free form";
}
.uploadcare--crop-sizes__item:nth-child(2)::after {
  content: "Square";
}
.uploadcare--crop-sizes__item:nth-child(3)::after {
  content: "Portrait";
}
Crop preset names
Crop preset names

Add custom widget button labels

<input type="hidden" role="uploadcare-uploader" id="uploadcare-file-1" data-btn-text="I'm the first buton" />
<input type="hidden" role="uploadcare-uploader" id="uploadcare-file-2" data-btn-text="I'm the second one" />
<input type="hidden" role="uploadcare-uploader" id="uploadcare-file-3" data-btn-text="And I am the third" />
// get an array of widget references
const widgets = uploadcare.initialize();

// update each widget button text with the data-btn-text attribute's value
widgets.forEach(widget => {
  widget.inputElement.nextSibling.querySelector(".uploadcare--widget__button_type_open").innerHTML = widget.inputElement.getAttribute("data-btn-text");
});
Custom button captions
Custom button captions

Reset widget after upload

// get widget reference
const widget = uploadcare.Widget("[role=uploadcare-uploader]");

// once a file is uploaded, output its URL and reset the widget
widget.onUploadComplete(fileInfo => {
  console.log(fileInfo.cdnUrl);
  widget.value(null);
});

Add a custom message to the dialog

/* turn the "after" pseudo element of the dialog container's div into a hint */
.uploadcare--tab__content::after {
  content: "Wake up Neo... The Matrix has you... Follow the white rabbit🐇";
  padding: 1em;
  margin: 2em;
  background-color: #000;
  color: #00ff00;
  border-radius: 5px;
}
Custom hint message
Custom hint message