saveLabelData = function()

in app/assets/javascripts/labels_select.js [103:210]
79 lines of code
8 McCabe index (conditional complexity)

      saveLabelData = function() {
        var data, selected;
        selected = $dropdown
          .closest('.selectbox')
          .find("input[name='" + fieldName + "']")
          .map(function() {
            return this.value;
          })
          .get();

        if (_.isEqual(initialSelected, selected)) return;
        initialSelected = selected;

        data = {};
        data[abilityName] = {};
        data[abilityName].label_ids = selected;
        if (!selected.length) {
          data[abilityName].label_ids = [''];
        }
        $loading.removeClass('hidden').fadeIn();
        $dropdown.trigger('loading.gl.dropdown');
        axios
          .put(issueUpdateURL, data)
          .then(({ data }) => {
            var labelCount, template, labelTooltipTitle, labelTitles, formattedLabels;
            $loading.fadeOut();
            $dropdown.trigger('loaded.gl.dropdown');
            $selectbox.hide();
            data.issueUpdateURL = issueUpdateURL;
            labelCount = 0;
            if (data.labels.length && issueUpdateURL) {
              template = LabelsSelect.getLabelTemplate({
                labels: data.labels,
                issueUpdateURL,
                enableScopedLabels: scopedLabels,
                scopedLabelsDocumentationLink,
              });
              labelCount = data.labels.length;

              // EE Specific
              if (isEE) {
                /**
                 * For Scoped labels, the last label selected with the
                 * same key will be applied to the current issueable.
                 *
                 * If these are the labels - priority::1, priority::2; and if
                 * we apply them in the same order, only priority::2 will stick
                 * with the issuable.
                 *
                 * In the current dropdown implementation, we keep track of all
                 * the labels selected via a hidden DOM element. Since a User
                 * can select priority::1 and priority::2 at the same time, the
                 * DOM will have 2 hidden input and the dropdown will show both
                 * the items selected but in reality server only applied
                 * priority::2.
                 *
                 * We find all the labels then find all the labels server accepted
                 * and then remove the excess ones.
                 */
                const toRemoveIds = Array.from(
                  $form.find(`input[type="hidden"][name="${fieldName}"]`),
                )
                  .map(el => el.value)
                  .map(Number);

                data.labels.forEach(label => {
                  const index = toRemoveIds.indexOf(label.id);
                  toRemoveIds.splice(index, 1);
                });

                toRemoveIds.forEach(id => {
                  $form
                    .find(`input[type="hidden"][name="${fieldName}"][value="${id}"]`)
                    .last()
                    .remove();
                });
              }
            } else {
              template = `<span class="no-value">${__('None')}</span>`;
            }
            $value.removeAttr('style').html(template);
            $sidebarCollapsedValue.text(labelCount);

            if (data.labels.length) {
              labelTitles = data.labels.map(function(label) {
                return label.title;
              });

              if (labelTitles.length > 5) {
                labelTitles = labelTitles.slice(0, 5);
                labelTitles.push(
                  sprintf(s__('Labels|and %{count} more'), { count: data.labels.length - 5 }),
                );
              }

              labelTooltipTitle = labelTitles.join(', ');
            } else {
              labelTooltipTitle = __('Labels');
            }

            $sidebarLabelTooltip.attr('title', labelTooltipTitle).tooltip('_fixTitle');

            $('.has-tooltip', $value).tooltip({
              container: 'body',
            });
          })
          .catch(() => flash(__('Error saving label update.')));
      };