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zarjay / JR's Utils

// ==UserScript==
// @name        JR's Utils
// @namespace   http://openuserjs.org/users/zarjay/scripts
// @author      zarjay
// @version     1.4.1
// @description Library of functions runnable in the browser console.
// @match       http://*/*
// @match       https://*/*
// @license     MIT License; https://github.com/zarjay/userscripts/blob/master/LICENSE
// @updateURL   https://openuserjs.org/meta/zarjay/JRs_Utils.meta.js
// ==/UserScript==

const exec = fn => {
	const script = document.createElement('script');
	script.textContent = `(${fn})()`;
	document.head.appendChild(script);
};

const main = () => {
	// add CSS to the page
	function css(content) {
		const element = document.createElement('style');
		element.textContent = content;
		document.head.appendChild(element);
	}

	// copy JavaScript to the clipboard
	function copyJS(js) {
		copy(stringifyJS(js));
	}

	// copy JSON to the clipboard
	function copyJSON(js) {
		copy(stringifyJSON(js));
	}

	// make the page editable or non-editable
	function edit(canEdit = true) {
		document.designMode = canEdit ? 'on' : 'off';
	}

	// count occurrences of each value
	function frequency(...values) {
		return values.reduce((obj, val) => Object.assign(obj, { [val]: (obj[val] || 0) + 1 }), {});
	}

	// add HTML to the page
	function html(content, position = 'beforeend') {
		document.body.insertAdjacentHTML(position, content);
	}

	// include JS/CSS from URL or CDN
	function include(asset, type) {
		if (!asset.includes('/')) return includeFromCDN(asset);
		return includeFromURL(asset, type);
	}

	// include JS/CSS file from CDN
	function includeFromCDN(library) {
		return fetch(`https://api.cdnjs.com/libraries?search=${library}`)
			.then(response => response.json())
			.then(json => json.results[0].latest)
			.then(includeFromURL)
			.catch(error => console.error(`Couldn't load ${library}`, error))
	}

	// include JS/CSS file from URL
	function includeFromURL(url, type = url.split('.').pop().toLowerCase()) {
		return new Promise((resolve, reject) => {
			let element;

			if (type === 'css') {
				element = document.createElement('link');
				element.rel = 'stylesheet';
				element.href = url;
			} else if (type === 'js') {
				element = document.createElement('script');
				element.src = url;
				element.async = false;
			} else {
				throw new Error(`Failed to include ${url} due to unknown file type.`);
			}

			element.onload = resolve;
			element.onerror = reject;
			document.head.appendChild(element);
		}).then(() => console.log('Loaded', url));
	}

	const defaultEvents = [
		'contextmenu',
		'copy',
		'keydown',
		'keypress',
		'keyup',
		'mousedown',
		'mouseup',
		'paste',
		'selectstart'
	];

	// block bubble events with a capture event
	function intercept(target = document.documentElement, events = defaultEvents) {
		const stopEvents = event => event.stopPropagation();
		query(target).forEach(element =>
			events.forEach(event => element.addEventListener(event, stopEvents, true)));
	}

	// add JS to the page
	function js(content, isImmediate = false) {
		const script = document.createElement('script');
		script.textContent = isImmediate ? `(${content})()` : content;
		document.head.appendChild(script);
	}

	// calculate the mean
	function mean(...values) {
		return sum(...values) / values.length;
	}

	// calculate the median
	function median(...values) {
		values.sort((a, b) => a - b);
		const low = (values.length - 1) >> 1;
		const high = values.length >> 1;
		return (values[low] + values[high]) / 2;
	}

	// calculate the mode
	function mode(...values) {
		const counted = frequency(...values);
		const keys = unique(...values);
		const vals = keys.map(x => counted[x]);
		if (vals.every(x => x < 2)) return [];
		const max = Math.max(...vals);
		return keys.reduce((array, key) => counted[key] === max ? [...array, key] : array, []);
	}

	// pause audio/video (pause everything by default)
	function pause(target = 'audio, video') {
		const elements = query(target);
		elements.forEach(element => typeof element.pause === 'function' ? element.pause() : null);
	}

	// play audio/video (plays first found by default)
	function play(target = 'audio, video') {
		const element = query(target)[0];
		if (element && typeof element.play === 'function') element.play();
	}

	// kinda like jQuery's $()
	function query(target) {
		if (typeof target === 'string') return [...document.querySelectorAll(target)];
		if (target instanceof Node) return [target];
		return Array.from(target); // hopefully a NodeList, HTMLCollection, or Array
	}

	// format JS into a string
	function stringifyJS(js) {
		if (typeof js === 'function') {
			return js.toString();
		} else if (typeof js === 'object') {
			return stringifyJSON(js).replace(/"(\w+)":/g, '$1:').replace(/"/g, '\'');
		} else {
			return js;
		}
	}

	// format JSON into a string
	function stringifyJSON(js) {
		return JSON.stringify(js, null, '\t');
	}

	// calculate the sum
	function sum(...values) {
		return values.reduce((a, b) => a + b);
	}

	// filter out duplicate values
	function unique(...values) {
		return values.filter((x, i) => values.indexOf(x) === i)
	}

	const jr = {
		css,
		copyJS,
		copyJSON,
		edit,
		frequency,
		html,
		include,
		intercept,
		js,
		mean,
		median,
		mode,
		pause,
		play,
		query,
		sum,
		unique
	};

	if (window.jr) {
		console.warn('Userscript: jr variable is taken.');
	} else {
		window.jr = jr;
		console.log('Userscript: jr is loaded.');
	}
};

exec(main);