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mutations

GitHub mutations observer library script

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/28721/1108163/mutations.js 

/* GitHub mutations observer library script v0.6.0
 * Detect changes to various elements and trigger an event
 * This script is meant to be used as a library for GitHub-based userscripts
 * Copyright © 2022 Rob Garrison
 * License: MIT
 */
(() => {
	"use strict";

	// prefix for event & document body class name, e.g. "ghmo:container"
	const prefix = "ghmo";
	const disableAttr = `data-${prefix}-disable`;
	const debounceInterval = 250;
	const targets = {
		// pjax container (covers general, repo & gists)
		// .news = newsfeed layout
		// .repository-content = file code (code folding)
		// body = global changes
		"[data-pjax-container], .news, .repository-content, body": {
			count: 0,
			name: "container"
		},
		// comment preview active
		".js-preview-body": {
			count: 0,
			name: "preview"
		},
		// .js-discussion = wrapper for progressively loaded comments;
		// "# items not shown" example: https://github.com/isaacs/github/issues/18
		// .discussion-item = issue status changed (github-issue-show-status)
		// #progressive-timeline-item-container = load hidden items (old?)
		// #js-progressive-timeline-item-container = load hidden items
		// markdown-toolbar = issue comments
		".js-discussion, .discussion-item, .toolbar-item, #progressive-timeline-item-container, #js-progressive-timeline-item-container, markdown-toolbar": {
			count: 0,
			name: "comments"
		},
		// progressively loaded content (diff files)
		".js-diff-progressive-container, .data.blob-wrapper, .js-diff-load-container, .diff-table tbody, .diff-progressive-loader": {
			count: 0,
			name: "diff"
		},
		// issues/pr sidebar & timeline sections: e.g. form actions, commit
		// references, deployment state & PR checks container
		".js-updatable-content, .js-updatable-content-preserve-scroll-position": {
			count: 0,
			name: "updatable"
		},
		// user profile menu (loads on hover)
		"details-menu": {
			count: 0,
			name: "menu"
		}
	};
	const list = Object.keys(targets);
	let queue = new Set();
	let timer;

	function fireEvents() {
		list.forEach(selector => {
			if (targets[selector].count > 0) {
				// event => "ghmo:container", "ghmo:comments"
				const event = new Event(prefix + ":" + targets[selector].name);
				document.dispatchEvent(event);
				targets[selector].count = 0;
			}
		});
	}

	function process() {
		clearTimeout(timer);
		// avoiding use of forEach loops for performance reasons
		for (const target of queue) {
			if (target) {
				for (const item of list) {
					if (target.matches(item)) {
						targets[item].count++;
					}
				}
			}
		}
		timer = setTimeout(() => fireEvents(), debounceInterval);
		queue.clear();
	}

	function init() {
		// prevent error when library is loaded at document-start & no body exists
		const container = document.querySelector("body");
		/* document.body attribute used to disable updates; it *should not*
		 * be used regularly as multiple scripts may enable or disable the
		 * observers at inappropriate times. It is best that each script handles
		 * the mutation events triggered by this library on its own
		 */
		if (container.getAttribute(disableAttr)) {
			return;
		}
		// prevent script from installing more than once
		if (container && !container.classList.contains(prefix + "-enabled")) {
			container.classList.add(prefix + "-enabled");
			// http://stackoverflow.com/a/39332340/145346
			new MutationObserver(mutations => {
				if (!queue.size) {
					requestAnimationFrame(process);
				}
				for (const mutation of mutations) {
					queue.add(mutation.target);
				}
			}).observe(document, {
				childList: true,
				subtree: true,
			});
		}
	}

	if (document.readyState === "loading") {
		document.addEventListener("DOMContentLoaded", () => init);
	} else {
		init();
	}
})();