React Native File upload using XMLHttpRequest

upload_snap.js

_uploadSnap() {
  var url = 'http://example.com/upload'; // File upload web service path
  var photo = {
      uri: this.state.picturePath, // CameralRoll Url
      type: 'image/jpeg',
      name: 'photo.jpg',
  };

  var formData = new FormData();
  formData.append("file", photo);

  var xhr = new XMLHttpRequest();
  xhr.open('POST', url);
  console.log('OPENED', xhr.status);

  xhr.onprogress = function () {
      console.log('LOADING', xhr.status);
  };

  xhr.onload = function () {
      console.log('DONE', xhr.status);
  };
  
  xhr.setRequestHeader('authorization', this.state.token);
  xhr.send(formData);
}

See: https://github.com/facebook/react-native/blob/master/Libraries/Network/FormData.js#L28