code: function SingleInput(options) {
      Selectivity.call(
          this,
          assign(
              {
                  // Dropdowns for single-value inputs should open below the select box, unless there
                  // is not enough space below, in which case the dropdown should be moved up just
                  // enough so it fits in the window, but never so much that it reaches above the top.
                  positionDropdown: function(el, selectEl) {
                      var rect = selectEl.getBoundingClientRect();
                      var dropdownTop = rect.bottom;
  
                      var deltaUp = Math.min(
                          Math.max(dropdownTop + el.clientHeight - window.innerHeight, 0),
                          rect.top + rect.height
                      );
  
                      assign(el.style, {
                          left: rect.left + 'px',
                          top: dropdownTop - deltaUp + 'px',
                          width: rect.width + 'px'
                      });
                  }
              },
              options
          )
      );
  
      this.rerender();
  
      if (options.showSearchInputInDropdown === false) {
          this.initInput(this.$('.selectivity-single-select-input'), { search: false });
      }
  
      this.events.on({
          change: this.rerenderSelection,
          click: this._clicked,
          'click .selectivity-search-input': stopPropagation,
          'click .selectivity-single-selected-item-remove': this._itemRemoveClicked,
          'focus .selectivity-single-select-input': this._focused,
          'selectivity-selected': this._resultSelected
      });
  }
docs: SingleInput Constructor.