matches-closest.js

var vendor = Element.prototype.matches || Element.prototype.msMatchesSelector

function matches (el, selector) {
  if (!el || el.nodeType !== 1) return false;
  if (vendor) return vendor.call(el, selector);
  return false;
}

function closest (element, selector) {
  var parent = element

  while (parent && parent !== document) {
    if (matches(parent, selector)) return parent;
    parent = parent.parentNode
  }
}

document.addEventListener('click', function (event) {
  console.log(matches(event.target, '.add-to-cart .btn-cart'))
})