jQuery: Gets all event handlers bound to a DOM Element

getEventHandlers.js

/**
 * Gets all event-handlers from a DOM element.
 * Events with namespace are allowed.
 *
 * @param  {Element} node: DOM element
 * @param  {String} eventns: (optional) name of the event/namespace
 * @return {Object}
 */
function getEventHandlers(element, eventns) {
  const $ = window.jQuery;
  const i = (eventns || '').indexOf('.'),
    event = i > -1 ? eventns.substr(0, i) : eventns,
    namespace = i > -1 ? eventns.substr(i + 1) : void(0),
    handlers = Object.create(null);
  element = $(element);
  if (!element.length) return handlers;
  // gets the events associated to a DOM element
  const listeners = $._data(element.get(0), "events") || handlers;
  const events = event ? [event] : Object.keys(listeners);
  if (!eventns) return listeners; // Object with all event types
  events.forEach((type) => {
    // gets event-handlers by event-type or namespace
    (listeners[type] || []).forEach(getHandlers, type);
  });
  // eslint-disable-next-line
  function getHandlers(e) {
    const type = this.toString();
    const eNamespace = e.namespace || (e.data && e.data.handler);
    // gets event-handlers by event-type or namespace
    if ((event === type && !namespace) ||
        (eNamespace === namespace && !event) ||
        (eNamespace === namespace && event === type)) {
      handlers[type] = handlers[type] || [];
      handlers[type].push(e);
    }
  }
  return handlers;
}

usage.js

// get all event handlers bound to the DOMElement
getEventHandlers(document);

// get all "click" event handlers bound to the DOMElement
getEventHandlers("#my-form", "submit");

// getall "click" event handlers having the namespace ".cbox"
getEventHandlers(document, 'click.cbox')

// get all event handlers with the namespace ".cbox"
getEventHandlers(document, '.cbox')