Feature is implemented yet via flash - thanks to the author of FileAPI plugin.
// bind to your upload container
var el = document.getElementById('uploadElementId');
FileAPI.event.on(el, 'change', function (evt/**Event*/) {
var files = FileAPI.getFiles(evt);
// get Data URL for the first file
FileAPI.readAsDataURL(files[0], function (dataUrlObject) {
if (dataUrlObject.type == 'load') {
// Success
var dataUrl = dataUrlObject.result;
}
});
});
Whole thread here: https://github.com/mailru/FileAPI/issues/153