_appendOptionWithIcon(select, option, type) {
      // Add disabled attr if disabled
      let disabledClass = option.disabled ? 'disabled ' : '';
      let optgroupClass = type === 'optgroup-option' ? 'optgroup-option ' : '';
      let multipleCheckbox = this.isMultiple
        ? `<label><input type="checkbox"${disabledClass}"/><span>${option.innerHTML}</span></label>`
        : option.innerHTML;
      let liEl = $('<li></li>');
      let spanEl = $('<span></span>');
      spanEl.html(multipleCheckbox);
      liEl.addClass(`${disabledClass} ${optgroupClass}`);
      liEl.append(spanEl);

      // add icons
      let iconUrl = option.getAttribute('data-icon');
      if (!!iconUrl) {
        let imgEl = $(`<img alt="" src="${iconUrl}">`);
        liEl.prepend(imgEl);
      }

      // Check for multiple type.
      $(this.dropdownOptions).append(liEl[0]);
      return liEl[0];
    }
Setup dropdown
@param {Element} select  select element
@param {Element} option  option element from select
@param {String} type
@return {Element}  option element added