_pickerWithSelectboxForAddEvent(selectlist, optionlist) {
    optionlist.addEventListener('click', (event) => {
      const optionValue = event.target.getAttribute('data-item');
      const fireEvent = document.createEvent('HTMLEvents');

      selectlist.querySelector(`[value="${optionValue}"]`).selected = true;
      fireEvent.initEvent('change', true, true);

      selectlist.dispatchEvent(fireEvent);

      this.selectBoxShow = false;
      optionlist.style.display = 'none';
    });

    selectlist.addEventListener('mousedown', (event) => {
      event.preventDefault();
      this.selectBoxShow = !this.selectBoxShow;
      optionlist.style.display = this.selectBoxShow ? 'block' : 'none';
      optionlist.setAttribute('data-selectitem', selectlist.value);
      optionlist.querySelector(`[data-item='${selectlist.value}']`).classList.add('active');
    });
  }
custom selectbox custom event
@param {HTMLElement} selectlist - selectbox element
@param {HTMLElement} optionlist - custom option list item element
@private