Source: delegate/delegate.es.js

  1. /**
  2.  * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
  3.  *
  4.  * This library is free software; you can redistribute it and/or modify it under
  5.  * the terms of the GNU Lesser General Public License as published by the Free
  6.  * Software Foundation; either version 2.1 of the License, or (at your option)
  7.  * any later version.
  8.  *
  9.  * This library is distributed in the hope that it will be useful, but WITHOUT
  10.  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  11.  * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  12.  * details.
  13.  */
  15. /**
  16.  * Checks if element is disabled or whether it exists in a disabled element tree
  17.  * @param {!Element} element The DOM element to check.
  18.  * @return {boolean}
  19.  */
  20. function isDisabled(node) {
  21. 	return !!(node.disabled || node.closest('[disabled]'));
  22. }
  24. /**
  25.  * Listens to the specified event on the given DOM element, but only calls the
  26.  * given callback listener when it's triggered by elements that match the
  27.  * given selector or target element.
  28.  * @param {!Element} element The DOM element the event should be listened on.
  29.  * @param {string} eventName The name of the event to listen to.
  30.  * @param {string} selector Css selector that should match the event for the
  31.  *     listener to be triggered.
  32.  * @param {!function(!Object)} callback Function to be called when the event
  33.  *     is triggered. It will receive the normalized event object.
  34.  * @return {function} Can be used to remove the listener.
  35.  */
  36. function delegate(element, eventName, selector, callback) {
  37. 	const eventHandler = (event) => {
  38. 		const {defaultPrevented, target} = event;
  40. 		if (defaultPrevented || (eventName === 'click' && isDisabled(target))) {
  41. 			return;
  42. 		}
  44. 		const delegateTarget = target.closest(selector);
  46. 		if (delegateTarget) {
  47. 			event.delegateTarget = delegateTarget;
  49. 			callback(event);
  50. 		}
  51. 	};
  53. 	element.addEventListener(eventName, eventHandler);
  55. 	return {
  56. 		dispose() {
  57. 			element.removeEventListener(eventName, eventHandler);
  58. 		},
  59. 	};
  60. }
  62. export default delegate;