IMDb Standard Deviation

Adds standard deviation to IMDb ratings breakdown pages.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         IMDb Standard Deviation
// @namespace    http://userscripts.org/users/7063
// @include      https://www.imdb.com/title/tt*/ratings
// @include      https://www.imdb.com/title/tt*/ratings/
// @include      https://www.imdb.com/title/tt*/ratings-*
// @include      https://www.imdb.com/title/tt*/ratings?*
// @version      2025.1.13.4.31
// @grant        none
// @description  Adds standard deviation to IMDb ratings breakdown pages.
// @noframes
// ==/UserScript==

(function () {
    "use strict";
	function go(main) {
		const votes = [...main.querySelectorAll(".VictoryContainer path ~ text")].map(k => {
			const text = k.textContent.match(/\((.*)\)/)[1];
			const km = text.match(/[KM]/);
			if (km) {
				return +text.match(/[^KM]+/) * 10 ** {"K": 3, "M": 6}[km];
			}
			return +text;
		});
		const [product, votecount] = votes.reduce(
			([p, v], c, i) => [p + c * (10 - i), v + c],
			[0, 0]
		);
		const sumOfSquares = votes.reduce(
			(p, c, i) => p + Math.pow(10 - i - product / votecount, 2) * c,
			0
		);
        const p = document.createElement("p");
		p.textContent = `${Math.sqrt(sumOfSquares / (votecount - 1)).toFixed(2)} Standard deviation`;
		p.classList.add("cSLvSW");
		main.append(p);
	}
	const obParams = [document.body, { childList: true, subtree: true }];
	const observer = new MutationObserver(() => {
		observer.disconnect();
		const histo = document.querySelector(`[data-testid="histogram-container"]`);
		if (histo) {
			go(histo);
		} else {
			observer.observe(...obParams);
		}
	});
	observer.observe(...obParams);

}());