​

const addElementBtn = document.querySelector('#addElement');

​

addElementBtn.addEventListener('click', () => {

  const newElement = document.createElement('div');

  newElement.classList.add('sortable-item');

  newElement.textContent = 'New Element';

​

  const sortableElement = document.getElementById('sortable');

  const instanceSortable = Sortable.getInstance(sortableElement);

  instanceSortable.addIem(newElement);

  alert('Element added');

});

​

​