Detect CSS Ellipsis in JavaScript and add a title. https://jsfiddle.net/tzi/qtqnqomL/

isEllipsisActive.js

// https://jsfiddle.net/tzi/qtqnqomL/

function isEllipsisActive(element) {
  return element.offsetWidth < element.scrollWidth;
}

Array.from(document.querySelectorAll('.ellipsis'))
  .forEach(element => {
    if (isEllipsisActive(element)) {
      element.title = element.innerText;
    }
  });