Lepro Total Comments JS

lepro total comments JS
当前为 2016-07-05 提交的版本，查看最新版本。
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// ==UserScript==
// @name         Lepro Total Comments JS
// @description  lepro total comments JS
// @license      MIT
// @namespace    leprosorium.ru
// @include      http://leprosorium.ru/comments/*
// @include      http://*.leprosorium.ru/comments/*
// @include      http*://leprosorium.ru/comments/*
// @include      http*://*.leprosorium.ru/comments/*
// @copyright    2016, lynxtaa
// @grant        none
// @version      1.2
// ==/UserScript==


var BEST_TRESHOLD = 0.75;

var controls = document.getElementById('js-comments').querySelector('.b-comments_controls'),
	comments_holder = document.getElementById('js-comments_holder'),
	style = document.createElement('style'),
	best = document.createElement('a'),
	all = document.createElement('a'),
	std_dev,
	best_count;

style.textContent = ".is_hidden { display: none; }";
document.body.appendChild(style);


// Кнопки управления
best.textContent = 'лучшие';
all.textContent = 'все';
controls.appendChild(best);
controls.appendChild(all);


// Лучшее
best.addEventListener('click', function(e) {
	e.preventDefault();
	if (this.className === 'active') {
		return false;
	} else if (std_dev) {
		document.body.appendChild(style);
	} else {
		var votes = comments_holder.querySelectorAll('strong.vote_result');
		var	rating;
		best_count = votes.length;
		std_dev = (getStdDev(votes) || 0.1);
		for (var i = 0; i < votes.length; i++) {
			rating = parseInt(votes[i].textContent);
			if ( rating > 0 && (rating / std_dev) < BEST_TRESHOLD) {
				hideComment(votes[i]);
			}
		}
		this.setAttribute('title', best_count);
	}

	this.className = 'active';
	this.nextSibling.className = '';
}, false);


// Показать всё
all.addEventListener('click', function(e) {
	e.preventDefault();
	if (std_dev && this.className !== 'active') {
		this.className = 'active';
		this.previousSibling.className = '';
		document.body.removeChild(style);
	}
}, false);


// Среднеквадратическое отклонение
function getStdDev(votes) {
	var	abovenull = 0,
		rating_square_sum = 0,
		rating_sum = 0,
		rating;

	for (var i = 0; i < votes.length; i++) {
		rating = parseInt(votes[i].textContent);
		if ( rating > 0 ) {
			abovenull++;
			rating_sum += rating;
			rating_square_sum += Math.pow(rating, 2);
		} else {
			hideComment(votes[i]);
		}
	}
	
	abovenull = (abovenull || 1);
	return Math.sqrt( (rating_square_sum / abovenull) -
				Math.pow((rating_sum / abovenull), 2) );
}


// Прячем
function hideComment(el) {
	while (!el.classList.contains('comment')) {
		el = el.parentNode;
		if (el === document) {
			throw new Error('Can\'t find comment container.');
		}
	}
	el.classList.add('is_hidden');
	best_count--;
}