delegate-event-listener/esm/index.js

Delegate event listener.

/**
 * Determine if a DOM element matches a CSS selector
 *
 * @param {Element} elem
 * @param {String} selector
 * @return {Boolean}
 * @api public
 */

function matches(elem, selector) {
  // Vendor-specific implementations of `Element.prototype.matches()`.
  var proto = window.Element.prototype;
  var nativeMatches = proto.matches ||
      proto.mozMatchesSelector ||
      proto.msMatchesSelector ||
      proto.oMatchesSelector ||
      proto.webkitMatchesSelector;

  if (!elem || elem.nodeType !== 1) {
    return false;
  }

  var parentElem = elem.parentNode;

  // use native 'matches'
  if (nativeMatches) {
    return nativeMatches.call(elem, selector);
  }

  // native support for `matches` is missing and a fallback is required
  var nodes = parentElem.querySelectorAll(selector);
  var len = nodes.length;

  for (var i = 0; i < len; i++) {
    if (nodes[i] === elem) {
      return true;
    }
  }

  return false;
}

/**
 * Expose `matches`
 */

var domMatches = matches;

/**
 * Module dependencies
 */



/**
 * @param element {Element}
 * @param selector {String}
 * @param context {Element}
 * @return {Element}
 */
var domClosest = function (element, selector, context) {
  context = context || document;
  // guard against orphans
  element = { parentNode: element };

  while ((element = element.parentNode) && element !== context) {
    if (domMatches(element, selector)) {
      return element;
    }
  }
};

var disabledElementsSelector = ['input', 'textarea', 'button', 'select', 'form'].map(function (element) {
  return "".concat(element, "[disabled]");
}).join(',');
var eventNameMap = {
  focus: 'focusin',
  blur: 'focusout',
  mouseenter: 'mouseover',
  mouseleave: 'mouseout',
  pointerenter: 'pointerover',
  pointerleave: 'pointerout'
};
var index = (function () {
  for (var _len = arguments.length, arguments_ = new Array(_len), _key = 0; _key < _len; _key++) {
    arguments_[_key] = arguments[_key];
  }

  var handleEventName = arguments_.length === 3;

  if (!handleEventName) {
    arguments_.unshift(null);
  }

  var eventName = arguments_[0],
      selector = arguments_[1],
      listener = arguments_[2];

  var wrappedListener = function wrappedListener(e) {
    if (selector === '') {
      e.delegateTarget = e.target;

      if (handleEventName) {
        e.originalEventType = eventName;
      }

      listener(e);
      return;
    }

    var disabledAncestor = domClosest(e.target, disabledElementsSelector);
    var closestNode = domClosest(e.target, selector);
    var isDelegated = !e.currentTarget.contains(disabledAncestor) && e.currentTarget.contains(closestNode) && e.currentTarget !== e.target;

    if (isDelegated) {
      e.delegateTarget = closestNode;

      if (handleEventName) {
        e.originalEventType = eventName;
      }

      if (handleEventName && typeof eventNameMap[eventName] !== 'undefined' && eventName !== 'focus' && eventName !== 'blur') {
        var delegateTarget = e.delegateTarget;
        var relatedTarget = e.relatedTarget;

        if (!relatedTarget || !delegateTarget.contains(relatedTarget)) {
          listener(e);
        }
      } else {
        listener(e);
      }
    }
  };

  if (handleEventName) {
    var _eventNameMap$eventNa;

    return [(_eventNameMap$eventNa = eventNameMap[eventName]) !== null && _eventNameMap$eventNa !== void 0 ? _eventNameMap$eventNa : eventName, wrappedListener];
  }

  return wrappedListener;
});

export default index;
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