latex-render-toggle.user.js

// ==UserScript==
// @name         LaTeX Render Toggle
// @author       eWloYW8
// @version      1.4
// @description  在网页上添加开关动态开启/关闭 LaTeX 渲染（MathJax、KaTeX、Wikipedia）。
// @match        *://*/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    let latexEnabled = true;

    function extractKatexSource(k) {
        if (k.dataset.latexSrc) return k.dataset.latexSrc;
        const annotation = k.querySelector(".katex-mathml annotation");
        if (annotation && annotation.textContent.trim()) {
            k.dataset.latexSrc = annotation.textContent.trim();
            return k.dataset.latexSrc;
        }
        const math = k.querySelector(".katex-mathml math");
        if (math && math.lastChild && math.lastChild.nodeType === Node.TEXT_NODE) {
            k.dataset.latexSrc = math.lastChild.textContent.trim();
            return k.dataset.latexSrc;
        }
        return null;
    }

    function extractMathJaxSource(node) {
        if (node.dataset.latexSrc) return node.dataset.latexSrc;
        let source = null;
        const script = node.nextElementSibling;
        if (script && script.tagName === 'SCRIPT' && script.type.startsWith('math/tex')) {
            source = script.textContent.trim();
        }
        if (!source && node.dataset.tex) {
            source = node.dataset.tex;
        }
        if (!source) {
            const innerScript = node.querySelector('script[type^="math/tex"]');
            if (innerScript && innerScript.textContent.trim()) {
                source = innerScript.textContent.trim();
            }
        }
        if (source) {
            node.dataset.latexSrc = source;
            return source;
        }
        return null;
    }

    function extractWikipediaSource(el) {
        if (el.dataset.latexSrc) return el.dataset.latexSrc;
        let source = null;
        const annotation = el.querySelector("annotation[encoding='application/x-tex']");
        if (annotation && annotation.textContent.trim()) {
            source = annotation.textContent.trim();
        }
        if (!source) {
            const img = el.querySelector("img.mwe-math-fallback-image-inline");
            if (img && img.alt) {
                source = img.alt.trim();
            }
        }
        if (source) {
            el.dataset.latexSrc = source;
            return source;
        }
        return null;
    }

    function getAssociatedScript(mathJaxElement) {
        const script = mathJaxElement.nextElementSibling;
        if (script && script.tagName === 'SCRIPT' && script.type.startsWith('math/tex')) {
            return script;
        }
        return mathJaxElement.querySelector('script[type^="math/tex"]');
    }

    function disableLatexFor(el) {
        if (el.dataset.processed === '1') return;
        let latex = null;
        let associatedScript = null;

        if (el.classList.contains('katex')) {
            latex = extractKatexSource(el);
        } else if (el.classList.contains('MathJax')) {
            latex = extractMathJaxSource(el);
            associatedScript = getAssociatedScript(el);
        } else if (el.classList.contains('mwe-math-element')) {
            latex = extractWikipediaSource(el);
        }

        if (!latex) return;

        if (!el.previousElementSibling || !el.previousElementSibling.classList.contains('latex-raw')) {
            const span = document.createElement('span');
            span.className = 'latex-raw';
            span.textContent = latex;
            span.style.whiteSpace = 'pre-wrap';
            span.style.fontFamily = 'Consolas, monospace';
            el.insertAdjacentElement('beforebegin', span);
        }

        el.style.display = 'none';
        el.dataset.processed = '1';

        if (associatedScript) {
            associatedScript.style.display = 'none';
            associatedScript.dataset.processed = '1';
        }
    }

    function enableLatexFor(el) {
        const raw = el.previousElementSibling;
        if (raw && raw.classList.contains('latex-raw')) {
            raw.remove();
        }
        el.style.display = '';
        el.dataset.processed = '0';

        if (el.classList.contains('MathJax')) {
            const associatedScript = getAssociatedScript(el);
            if (associatedScript) {
                associatedScript.style.display = '';
                associatedScript.dataset.processed = '0';
            }
        }
    }

    function applyToggle() {
        const nodes = document.querySelectorAll('.katex, .MathJax, .mwe-math-element');
        nodes.forEach(el => latexEnabled ? enableLatexFor(el) : disableLatexFor(el));
    }

    const btn = document.createElement('button');
    btn.textContent = 'Disable LaTeX';
    btn.style.cssText = `
        position: fixed;
        bottom: 20px;
        right: 20px;
        padding: 8px 12px;
        background: #444;
        color: #fff;
        border: none;
        border-radius: 6px;
        z-index: 999999;
        cursor: pointer;
        opacity: 0.9;
    `;
    btn.style.display = 'none';
    document.body.appendChild(btn);

    function toggleLatex() {
        latexEnabled = !latexEnabled;
        btn.textContent = latexEnabled ? 'Disable LaTeX' : 'Enable LaTeX';
        applyToggle();
    }

    btn.onclick = toggleLatex;

    document.addEventListener('keydown', function(event) {
        if (event.altKey && event.key === 'l') {
            if (btn.style.display !== 'none') {
                event.preventDefault();
                toggleLatex();
            }
        }
    });

    function checkAndShowButton() {
        if (btn.style.display !== 'none') return;
        const selector = '.katex, .MathJax, .mwe-math-element';
        if (document.querySelector(selector)) {
            btn.style.display = '';
        }
    }

    const observer = new MutationObserver(mutations => {
        let needsToggle = false;
        const selector = '.katex, .MathJax, .mwe-math-element';
        for (const m of mutations) {
            for (const n of m.addedNodes) {
                if (!(n instanceof HTMLElement)) continue;
                if (n.matches(selector) || n.querySelector(selector)) {
                    needsToggle = true;
                }
            }
        }
        if (needsToggle) {
            applyToggle();
            checkAndShowButton();
        }
    });
    observer.observe(document.body, { childList: true, subtree: true });

    applyToggle();
    checkAndShowButton();
})();