Piece of code to upload file

upload_pouch.js

      function uploadFile(data, type) {

        blobUtil.base64StringToBlob(data).then(function (blob) {

          db.putAttachment($scope.ngDocId, $scope.attachmentId, $scope.ngModelRev, blob, type).then(function (result) {
            $scope.ngModelRev = result.rev;
            loadPreview();
          }).catch(function (err) {
            console.log(err);
          });

        }).catch(function (err) {
          // image failed to load
        });

      }

      $scope.upload = function (files) {
        if (files && files.length) {
          var file = files[0];

          var reader = new FileReader();

          reader.onload = function (e) {
            var encodedData = reader.result.replace("data:" + file.type + ";base64,", '');
            uploadFile(encodedData, file.type);
          };

          reader.readAsDataURL(file);
        }
      };