Re-calculating Amazon ranks based on Laplace's rule of succession
// ==UserScript==
// @name Amazon-Ranking-Laplace
// @namespace http://github.com/ArmanJR
// @version 0.1
// @description Re-calculating Amazon ranks based on Laplace's rule of succession
// @author Arman
// @match https://www.amazon.com/*/dp/*
// @icon https://upload.wikimedia.org/wikipedia/commons/d/de/Amazon_icon.png
// @license MIT
// @grant none
// ==/UserScript==
(function() {
'use strict';
document.onreadystatechange = function () {
if (document.readyState === 'complete') {
var xpath = '//*[@id="acrPopover"]/span[1]/a/i[1]/span';
var ratingElement = document.evaluate(xpath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
var rating = parseFloat(ratingElement.innerHTML.split("o")[0]);
var xpath2 = '//*[@id="acrCustomerReviewText"]';
var numElement = document.evaluate(xpath2, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
var num = parseFloat(numElement.innerHTML.replace(',', '').split("r")[0]);var first = rating + (5 - rating) / (num + 1);
var second = first + (1 - first) / (num + 2);
document.querySelector('#averageCustomerReviews').innerHTML += ' <span style="color:red;">' + second.toString().substr(0, 4) + ' ';
}
}
})();