DropzoneJS is an open source library that provides drag’n’drop file uploads with image previews.

Features

• Multiple simultaneous file upload;
• Works out of the box;
• Upload files through a web screen or a REST URL;
• Drag & Drop;
• Click to Upload;
• Upload without submit (ajax submit);
• Launches an event every time a file has been successfully uploaded;
• In mobile, can launch both the camera app or the file manager;
• Available in all flavours: Traditional, Reactive and Mobile.

Traditional

https://www.outsystems.com/forge/component-overview/200/multiple-file-upload

Mobile

Just use the reactive component for mobile, it will work, however, in mobile, local file upload is not supported.

More features are available, just follow the patterns for already implemented features and visit the dropzone website for the full documentation.

Source 

https://www.dropzonejs.com/