A simple event delegation.

delegate.js

/**
 * A simple event delegation method.
 */

// closest method: https://gist.github.com/Alex1990/5547956babc593852c3a

function delegate(elem, type, selector, listener, capture) {
  listener._delegateWrapper = function(e) {
    if (e.delegateTarget = closest(e.target, selector, elem)) {
      listener.call(e.delegateTarget, e);
    }
  }
  addEvent(elem, type, listener._delegateWrapper, capture);
}

function undelegate(elem, type, listener, capture) {
  removeEvent(elem, type, listener._delegateWrapper, capture);
  delete listener._delegateWrapper;
}