can-util/dom/events/attributes/attributes.js

Common utilities for CanJS projects

'use strict';

var events = require("../events");
var isOfGlobalDocument = require("../../is-of-global-document/is-of-global-document");
var domData = require("../../data/data");
var getMutationObserver = require("can-globals/mutation-observer/mutation-observer");
var assign = require("can-assign");
var domDispatch = require("../../dispatch/dispatch");

var originalAdd = events.addEventListener,
	originalRemove = events.removeEventListener;

/**
 * @module {events} can-util/dom/events/attributes/attributes attributes
 * @parent can-util/dom/events/events
 *
 * Adds a listenable "attributes" event to DOM nodes, which fires when
 * the node's attributes change.
 *
 * ```js
 * var events = require("can-util/dom/events/events");
 * require("can-util/dom/events/attributes/attributes");
 * var el = document.createElement("div");
 *
 * function attributesHandler() {
 * 	console.log("attributes event fired");
 * }
 *
 * events.addEventListener.call(el, "attributes", attributesHandler, false);
 *
 * events.removeEventListener.call(el, "attributes", attributesHandler);
 * ```
 */
events.addEventListener = function(eventName){
	if(eventName === "attributes") {
		var MutationObserver = getMutationObserver();
		if( isOfGlobalDocument(this) && MutationObserver ) {
			var existingObserver = domData.get.call(this, "canAttributesObserver");
			if (!existingObserver) {
				var self = this;
				var observer = new MutationObserver(function (mutations) {
					mutations.forEach(function (mutation) {
						var copy = assign({}, mutation);
						domDispatch.call(self, copy, [], false);
					});

				});
				observer.observe(this, {
					attributes: true,
					attributeOldValue: true
				});
				domData.set.call(this, "canAttributesObserver", observer);
			}
		} else {
			domData.set.call(this, "canHasAttributesBindings", true);
		}
	}
	return originalAdd.apply(this, arguments);

};

events.removeEventListener = function(eventName){
	if(eventName === "attributes") {
		var MutationObserver = getMutationObserver();
		var observer;

		if(isOfGlobalDocument(this) && MutationObserver) {
			observer = domData.get.call(this, "canAttributesObserver");

			if (observer && observer.disconnect) {
				observer.disconnect();
				domData.clean.call(this, "canAttributesObserver");
			}
		} else {
			domData.clean.call(this, "canHasAttributesBindings");
		}
	}
	return originalRemove.apply(this, arguments);
};