Smart Text Justifier

Justifies everything unless they are centered or aligned to the right.

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 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         Smart Text Justifier
// @namespace    http://tampermonkey.net/
// @version      1.5
// @description  Justifies everything unless they are centered or aligned to the right.
// @author       Ȼaptain Jøhn “Søap” MacTavish
// @license      CC-BY-NC-SA-4.0
// @match        *://*/*
// @exclude      https://www.grok.com/*
// @exclude      https://www.chatgpt.com/*
// @grant        none
// ==/UserScript==


(
    function()
    {
        'use strict';

        const ProcessedElements = new WeakSet();

        const IgnoredTags = new Set
        ([
            'SCRIPT', 'STYLE', 'META', 'LINK', 'HEAD', 'TITLE', 'NOSCRIPT',
            'BR', 'HR', 'IMG', 'VIDEO', 'AUDIO', 'CANVAS', 'SVG', 'PATH',
            'IFRAME', 'OBJECT', 'EMBED', 'CODE', 'PRE', 'A', 'SPAN', 'BUTTON',
            'LABEL', 'INPUT', 'SELECT', 'H1', 'H2', 'H3', 'H4', 'H5', 'H6',
            'STRONG', 'B', 'I', 'EM', 'SMALL', 'SUB', 'SUP', 'KBD', 'ABBR',
            'CITE', 'DD', 'DT', 'NAV', 'HEADER', 'FOOTER'
        ]);

        const CheckAndQueueElement = (NodeToCheck, ElementsQueue) =>
        {
            if (!ProcessedElements.has(NodeToCheck) && !IgnoredTags.has(NodeToCheck.tagName))
            {
                ProcessedElements.add(NodeToCheck);

                const ComputedAlignment = window.getComputedStyle(NodeToCheck).textAlign;

                if (ComputedAlignment !== 'center' && ComputedAlignment !== 'right')
                {
                    ElementsQueue.push(NodeToCheck);
                }
            }
        };

        const ProcessElements = (Elements) =>
        {
            const ElementsToUpdate = [];

            // DOM READ PHASE: Prevents Layout Thrashing by batching all reads first.
            for (const Element of Elements)
            {
                if (Element.nodeType === 1)
                {
                    CheckAndQueueElement(Element, ElementsToUpdate);

                    const Children = Element.querySelectorAll('*');

                    for (const Child of Children)
                    {
                        CheckAndQueueElement(Child, ElementsToUpdate);
                    }
                }
            }

            // DOM WRITE PHASE: Applies styles without triggering style recalculations mid-loop.
            for (const Element of ElementsToUpdate)
            {
                Element.style.setProperty('text-align', 'justify', 'important');
                Element.style.setProperty('text-justify', 'inter-word', 'important');
            }
        };

        const InitializeObserver = () =>
        {
            const InitialElements = [ document.body ];
            ProcessElements(InitialElements);

            let PendingNodes = [];
            let IsProcessing = false;

            const ContentObserver = new MutationObserver
            (
                (Mutations) =>
                {
                    for (const Mutation of Mutations)
                    {
                        for (const Node of Mutation.addedNodes)
                        {
                            if (Node.nodeType === 1)
                            {
                                PendingNodes.push(Node);
                            }
                        }
                    }

                    if (!IsProcessing && PendingNodes.length > 0)
                    {
                        IsProcessing = true;

                        requestAnimationFrame
                        (
                            () =>
                            {
                                ProcessElements(PendingNodes);
                                PendingNodes = [];
                                IsProcessing = false;
                            }
                        );
                    }
                }
            );

            ContentObserver.observe
            (
                document.body,
                {
                    childList: true,
                    subtree: true
                }
            );
        };

        if (document.readyState === 'complete' || document.readyState === 'interactive')
        {
            InitializeObserver();
        }
        else
        {
            window.addEventListener('DOMContentLoaded', InitializeObserver);
        }
    }
)
();