event delegate without javascript library ie9+

event-delegate.js

function on(elSelector, eventName, selector, handler, useCapture) {
  const _useCapture = useCapture === undefined ? false : useCapture;
  const elements = document.querySelectorAll(elSelector);
  const addEventListener = function(element) {
    element.addEventListener(eventName, function(e) {
      for (let target = e.target; target && target != this; target = target.parentNode) {
        // loop parent nodes from the target to the delegation node
        let match = false;
        if (target.matches) {
          match = target.matches(selector);
        } else if (target.webkitMatchesSelector) {
          match = target.webkitMatchesSelector(selector);
        } else if (target.mozMatchesSelector) {
          match = target.mozMatchesSelector(selector);
        } else if (target.msMatchesSelector) {
          match = target.msMatchesSelector(selector);
        } else if (target.oMatchesSelector) {
          match = target.oMatchesSelector(selector);
        }
        if (match) {
          handler.call(target, e);
          break;
        }
      }
    }, _useCapture);
  };
  Array.prototype.forEach.call(elements, addEventListener);
}