JavaScript API — Files and uploads

  • This documentation is for the version 3.2.2 of the widget. If you're looking for the JavaScript for Widget v2 docs, check here.

Uploadcare Widget and JavaScript API work with file instances, which implement the jQuery promise interface. You can create a file instance via a new upload or by addressing existing files.

Creating a new file instance

A new file instance can be constructed by calling the fileFrom function. Where the first argument is one of the predefined identifiers, and the second argument holds a file source. Depending on the passed identifier, the function can start a new upload or return an instance of an existing file.

File instance from URL

Uploading a file from URL is done by passing the url identifier to the fileFrom function,

var file = uploadcare.fileFrom('url', '');

File instance from native object

Our JavaScript API supports uploading new files from native file objects. This is done by passing the object identifier to the fileFrom function.

var file = uploadcare.fileFrom('object', input.files[0]);

That method supports large file uploads (> 100MB) and checking upload progress. However, it will not work in outdated browsers, see browser support.

File instance from DOM

You can also upload files from input DOM elements. This is done by passing the input identifier to fileFrom. Uploading from such inputs works in all browsers but does not support large files and checking upload progress.

var file = uploadcare.fileFrom('input', input);

File instance from UUID or CDN URL

That is the case when a file instance is created from an existing file that has a UUID and hence a CDN URL. Any of those can be used as a file source in fileFrom. The proper identifier to pass to the function, here, is uploaded,

var file = uploadcare.fileFrom('uploaded', '61783708-7090-4d6a-b82b-81f98e40a327');

Wait until a file is available

Quite often, you want to ensure a file is there and ready before getting its instance. That is what the function is all about. It returns a fileInfo object.

file.done(function(fileInfo) {
  // Upload has successfully completed and a file is ready.
}).fail(function(error, fileInfo) {
  // Upload failed, or something else went wrong, a file is not ready.

The error argument in the fail callback is one of the following values, or a user-defined custom value, raised via validators.

  • 'baddata', invalid argument passed to file constructor
  • 'size', file size is too large
  • 'upload', error during upload
  • 'user', upload was canceled
  • 'info', error when fetching file information
  • 'deleted', file was deleted, also applicable to groups and files within

Checking the progress of a file upload

When handling larger files, there is a sense in checking their upload progress. The progress function does exactly that and returns an uploadInfo object.

file.progress(function(uploadInfo) {
  // State of your upload gets updated.
  // The callback is invoked at least once with a current state,
  // right after assignment.

You can also show a file uploading progress via a jQuery UI progressbar.

file.progress(function(uploadInfo) {
  $('#progress').progressbar('value', uploadInfo.progress);

Cancelling a file upload

Just use cancel in case you want to immediately stop any in-progress upload and all the events.


Object overview, fileInfo

Here is how a fileInfo object is structured,

uuidstringFile UUID.
namestringOriginal filename.
sizenumberFile size in bytes.

true, if the file is stored in Uploadcare, false otherwise.


true, if the file is an image, false otherwise.


Public CDN URL related to a file,
may contain processing operations.


A string holding existing URL modifiers, i.e.
processing operations in case those are present.
Null otherwise.

originalUrlstringOriginal file CDN URL with no modifiers.

Object holding original image properties, if your file is an image,
null otherwise. Properties:

  • width and height
  • format — JPEG, PNG, etc.
  • datetime_original, geo_location and orientation from EXIF
  • dpi — from either format properties or EXIF, if available

Object holding the info about a file source. For example, this can be a name of a social media, public URL, etc.

We do not store such information hence it is only available on the page where your file uploading happens.

Object overview, uploadInfo

Here is how an uploadInfo object is structured,


Current upload states: 'uploading', 'uploaded', or 'ready'.

uploadProgressnumberUpload progress as a value ranging from 0 to 1.

File ready state combines the progress of both upload and preparing info, as a value ranging from 0 to 1.

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