Function updateOptions

test/angular/1.5/angular.js:29764–29838

()

      }

      function updateOptions() {
        var previousValue = options && selectCtrl.readValue();

        // We must remove all current options, but cannot simply set innerHTML = null
        // since the providedEmptyOption might have an ngIf on it that inserts comments which we
        // must preserve.
        // Instead, iterate over the current option elements and remove them or their optgroup
        // parents
        if (options) {

          for (var i = options.items.length - 1; i >= 0; i--) {
            var option = options.items[i];
            if (isDefined(option.group)) {
              jqLiteRemove(option.element.parentNode);
            } else {
              jqLiteRemove(option.element);
            }
          }
        }

        options = ngOptions.getOptions();

        var groupElementMap = {};

        // Ensure that the empty option is always there if it was explicitly provided
        if (providedEmptyOption) {
          selectElement.prepend(emptyOption);
        }

        options.items.forEach(function addOption(option) {
          var groupElement;

          if (isDefined(option.group)) {

            // This option is to live in a group
            // See if we have already created this group
            groupElement = groupElementMap[option.group];

            if (!groupElement) {

              groupElement = optGroupTemplate.cloneNode(false);
              listFragment.appendChild(groupElement);

              // Update the label on the group element
              // "null" is special cased because of Safari
              groupElement.label = option.group === null ? 'null' : option.group;

              // Store it for use later
              groupElementMap[option.group] = groupElement;
            }

            addOptionElement(option, groupElement);

          } else {

            // This option is not in a group
            addOptionElement(option, listFragment);
          }