code: function () {
              var placeholder = this.getPlaceholder();
  
              if (this.opts.element.val() === "" && placeholder !== undefined) {
  
                  // check for a first blank option if attached to a select
                  if (this.select && this.select.find("option:first").text() !== "") return;
  
                  this.selection.find("span").html(this.opts.escapeMarkup(placeholder));
  
                  this.selection.addClass("select2-default");
  
                  this.selection.find("abbr").hide();
              }
          }
docs: single