function addHandler()

in src/site/assets/js/bootstrap.esm.js [425:471]

• 39 lines of code
• 15 McCabe index (conditional complexity)

function addHandler(element, originalTypeEvent, handler, delegationFn, oneOff) {
  if (typeof originalTypeEvent !== 'string' || !element) {
    return;
  }

  if (!handler) {
    handler = delegationFn;
    delegationFn = null;
  } // in case of mouseenter or mouseleave wrap the handler within a function that checks for its DOM position
  // this prevents the handler from being dispatched the same way as mouseover or mouseout does


  if (customEventsRegex.test(originalTypeEvent)) {
    const wrapFn = fn => {
      return function (event) {
        if (!event.relatedTarget || event.relatedTarget !== event.delegateTarget && !event.delegateTarget.contains(event.relatedTarget)) {
          return fn.call(this, event);
        }
      };
    };

    if (delegationFn) {
      delegationFn = wrapFn(delegationFn);
    } else {
      handler = wrapFn(handler);
    }
  }

  const [delegation, originalHandler, typeEvent] = normalizeParams(originalTypeEvent, handler, delegationFn);
  const events = getEvent(element);
  const handlers = events[typeEvent] || (events[typeEvent] = {});
  const previousFn = findHandler(handlers, originalHandler, delegation ? handler : null);

  if (previousFn) {
    previousFn.oneOff = previousFn.oneOff && oneOff;
    return;
  }

  const uid = getUidEvent(originalHandler, originalTypeEvent.replace(namespaceRegex, ''));
  const fn = delegation ? bootstrapDelegationHandler(element, handler, delegationFn) : bootstrapHandler(element, handler);
  fn.delegationSelector = delegation ? handler : null;
  fn.originalHandler = originalHandler;
  fn.oneOff = oneOff;
  fn.uidEvent = uid;
  handlers[uid] = fn;
  element.addEventListener(typeEvent, fn, delegation);
}