Adds Sci-Hub, LibGen, Anna's Archive, Sci-net, Semantic Scholar, Unpaywall, CORE, and EuropePMC to Google Scholar results
// ==UserScript== // @name Google Scholar to free PDFs // @namespace ScholarToSciHub // @version 1.33 // @description Adds Sci-Hub, LibGen, Anna's Archive, Sci-net, Semantic Scholar, Unpaywall, CORE, and EuropePMC to Google Scholar results // @author Bui Quoc Dung // @match https://scholar.google.*/* // @license AGPL-3.0-or-later // @grant GM.xmlHttpRequest // @connect * // ==/UserScript== const SCIHUB_URL = 'https://tesble.com/'; const LIBGEN_URL = 'https://libgen.la/'; const LIBGEN_SEARCH_URL = LIBGEN_URL + 'index.php?req='; const ANNA_URL = 'https://annas-archive.org'; const ANNA_SCIDB_URL = ANNA_URL + '/scidb/'; const ANNA_CHECK_URL = ANNA_URL + '/search?index=journals&q='; const SCINET_URL = 'https://sci-net.xyz/'; const CROSSREF_URL = 'https://api.crossref.org/works?query.title='; const SEMANTIC_API_SEARCH_BASE = 'https://api.semanticscholar.org/graph/v1/paper/search'; const SEMANTIC_API_SEARCH_QS = '?fields=title,url,openAccessPdf&limit=1&query='; const SEMANTIC_API_DOI_BASE = 'https://api.semanticscholar.org/graph/v1/paper/DOI:'; const SEMANTIC_API_DOI_QS = '?fields=title,url,openAccessPdf'; const SEMANTIC_FALLBACK = 'https://www.semanticscholar.org/search?q='; const UNPAYWALL_API_BASE = 'https://api.unpaywall.org/v2/'; const UNPAYWALL_API_QS = '?email='; const UNPAYWALL_EMAIL = '[email protected]'; const UNPAYWALL_FALLBACK = 'https://unpaywall.org/'; const CORE_API_SEARCH_BASE = 'https://api.core.ac.uk/v3/search/works/'; const CORE_API_SEARCH_QS = '?q=doi:'; const CORE_FALLBACK = 'https://core.ac.uk/search/?q='; const EUROPEPMC_API_BASE = 'https://www.ebi.ac.uk/europepmc/webservices/rest/search'; const EUROPEPMC_API_QS = '?query=DOI:'; const EUROPEPMC_API_FMT = '&format=json'; const EUROPEPMC_SEARCH = 'https://europepmc.org/search?query='; const DOI_REGEX = /\b(10\.\d{4,}(?:\.\d+)*\/(?:(?!["&'<>])\S)+)\b/gi; function httpRequest(details) { return new Promise((resolve, reject) => { GM.xmlHttpRequest({ ...details, onload: resolve, onerror: reject }); }); } function updateLink(span, text, href, isNo = false) { const link = document.createElement('a'); link.href = href; link.target = '_blank'; link.rel = 'noopener noreferrer'; link.style.fontSize = '15px'; if (isNo) link.style.color = 'gray'; link.innerHTML = text.replace('[PDF]', '<b>[PDF]</b>').replace('[Maybe]', '<b>[Maybe]</b>'); span.replaceWith(link); } function addLoadingIndicator(container) { const span = document.createElement('div'); span.textContent = 'Loading...'; span.style.marginBottom = '4px'; span.style.color = 'gray'; span.style.fontSize = '15px'; container.appendChild(span); return span; } async function titleToDOI(title) { const encodedTitle = encodeURIComponent(title.trim()); try { const crRes = await httpRequest({ method: 'GET', url: `${CROSSREF_URL}${encodedTitle}&rows=1` }); const data = JSON.parse(crRes.responseText); return data.message.items?.[0]?.DOI || null; } catch (err) { console.warn('titleToDOI error:', err); return null; } } function cleanDOI(doi) { const match = doi.match(/^10\.\d{4,}(?:\.\d+)*\/[^\s\/?#<>]+/); return match ? match[0] : doi.trim(); } async function fetchDOI(titleLink) { const url = titleLink.href; const title = titleLink.textContent; if (url.toLowerCase().match(/\.pdf($|\?)/i)) { return await titleToDOI(title); } const urlDOIMatch = url.match(DOI_REGEX); if (urlDOIMatch) { return cleanDOI(urlDOIMatch[0]); } try { const res = await httpRequest({ method: 'GET', url }); const html = res.responseText; const linkMatch = html.match(/<a[^>]+href=["']([^"']*doi\.org\/10\.[^"']+)["'][^>]*>/i); if (linkMatch) { const href = linkMatch[1]; const doi = href.match(DOI_REGEX)?.[0]; if (doi) return cleanDOI(doi); } const doiMatch = html.match(DOI_REGEX); if (doiMatch) return cleanDOI(doiMatch[0]); return await titleToDOI(title); } catch (err) { console.warn('fetchDOI error:', err); return null; } } // ==== Sources ==== async function checkLibgen(title, doi, span) { const trySearch = async (query) => { try { const res = await httpRequest({ method: 'GET', url: LIBGEN_SEARCH_URL + query }); const doc = new DOMParser().parseFromString(res.responseText, 'text/html'); const table = doc.querySelector('.table.table-striped'); const firstRow = table?.querySelector('tbody > tr'); const secondTd = firstRow?.querySelectorAll('td')?.[1]; const linkEl = secondTd?.querySelector('a[href^="edition.php?id="]'); if (linkEl) { const href = linkEl.getAttribute('href'); const detailUrl = LIBGEN_URL + href; const detailRes = await httpRequest({ method: 'GET', url: detailUrl }); const detailDoc = new DOMParser().parseFromString(detailRes.responseText, 'text/html'); const hasPDF = !!detailDoc.querySelector('table'); if (hasPDF) { updateLink(span, '[PDF] LibGen', LIBGEN_SEARCH_URL + query); return true; } } } catch {} return false; }; const encTitle = encodeURIComponent(title); if (!(await trySearch(encTitle)) && doi) { const encDOI = encodeURIComponent(doi); if (!(await trySearch(encDOI))) { updateLink(span, '[No] LibGen', LIBGEN_SEARCH_URL + encDOI, true); } } else if (!doi) { updateLink(span, '[No] LibGen', LIBGEN_SEARCH_URL + encTitle, true); } } async function checkSciHub(href, doi, span) { const tryURL = async (url) => { try { const res = await httpRequest({ method: 'GET', url }); if (/iframe|embed/.test(res.responseText)) { updateLink(span, '[PDF] Sci-Hub', url); return true; } } catch {} return false; }; if (!(await tryURL(SCIHUB_URL + href)) && doi) { if (!(await tryURL(SCIHUB_URL + doi))) { updateLink(span, '[No] Sci-Hub', SCIHUB_URL + doi, true); } } else if (!doi) updateLink(span, '[No] Sci-Hub', SCIHUB_URL + href, true); } async function checkAnna(doi, span, retry = 0) { const checkUrl = ANNA_CHECK_URL + encodeURIComponent(doi); const directUrl = ANNA_SCIDB_URL + doi; try { const res = await httpRequest({ method: 'GET', url: checkUrl }); const doc = new DOMParser().parseFromString(res.responseText, 'text/html'); const bodyText = doc.body.textContent; if (bodyText.includes("Rate limited") && retry < 10) { setTimeout(() => checkAnna(doi, span, retry + 1), 5000); return; } const found = doc.querySelector('.mt-4.uppercase.text-xs.text-gray-500') || [...doc.querySelectorAll('div.text-gray-500')].some(div => div.textContent.includes(doi)); if (found) { const res2 = await httpRequest({ method: 'GET', url: directUrl }); const doc2 = new DOMParser().parseFromString(res2.responseText, 'text/html'); const hasPDF = doc2.querySelector('.pdfViewer, #viewerContainer, iframe[src*="viewer.html?file="]'); updateLink(span, hasPDF ? '[PDF] Anna' : '[Maybe] Anna', directUrl); } else { updateLink(span, '[No] Anna', checkUrl, true); } } catch { updateLink(span, '[No] Anna', checkUrl, true); } } async function checkSciNet(doi, span) { try { const res = await httpRequest({ method: 'GET', url: SCINET_URL + doi }); updateLink(span, /iframe|pdf|embed/.test(res.responseText) ? '[PDF] Sci-net' : '[No] Sci-net', SCINET_URL + doi, !/pdf/.test(res.responseText)); } catch { updateLink(span, '[No] Sci-net', SCINET_URL + doi, true); } } async function checkSemanticScholar(title, span, doi = null) { const titleQuery = `${SEMANTIC_API_SEARCH_BASE}${SEMANTIC_API_SEARCH_QS}${encodeURIComponent(title)}`; try { const res = await httpRequest({ method: 'GET', url: titleQuery }); const data = JSON.parse(res.responseText); const paper = data?.data?.[0]; const pdfUrl = paper?.openAccessPdf?.url; if (pdfUrl) { updateLink(span, '[PDF] Semantic', pdfUrl); return; } } catch {} if (doi) { const doiQuery = `${SEMANTIC_API_DOI_BASE}${encodeURIComponent(doi)}${SEMANTIC_API_DOI_QS}`; try { const res = await httpRequest({ method: 'GET', url: doiQuery }); const data = JSON.parse(res.responseText); const pdfUrl = data?.openAccessPdf?.url; if (pdfUrl) { updateLink(span, '[PDF] Semantic', pdfUrl); return; } } catch {} } const fallbackUrl = `${SEMANTIC_FALLBACK}${encodeURIComponent(doi || title)}`; updateLink(span, '[No] Semantic', fallbackUrl, true); } async function checkUnpaywall(doi, span) { const url = `${UNPAYWALL_API_BASE}${encodeURIComponent(doi)}${UNPAYWALL_API_QS}${encodeURIComponent(UNPAYWALL_EMAIL)}`; try { const res = await httpRequest({ method: 'GET', url }); const data = JSON.parse(res.responseText); if (data?.is_oa && data.best_oa_location?.url) { updateLink(span, '[PDF] Unpaywall', data.best_oa_location.url); } else { updateLink(span, '[No] Unpaywall', UNPAYWALL_FALLBACK, true); } } catch { updateLink(span, '[No] Unpaywall', UNPAYWALL_FALLBACK, true); } } async function checkCore(doi, span) { const searchUrl = `${CORE_API_SEARCH_BASE}${CORE_API_SEARCH_QS}${encodeURIComponent(doi)}`; try { const res = await httpRequest({ method: 'GET', url: searchUrl, headers: { accept: 'application/json' } }); const data = JSON.parse(res.responseText); const result = data?.results?.find(r => r?.doi?.toLowerCase() === doi.toLowerCase()); const pdfUrl = result?.downloadUrl; if (pdfUrl) { updateLink(span, '[PDF] Core', pdfUrl); } else { updateLink(span, '[No] Core', `${CORE_FALLBACK}${encodeURIComponent(doi)}`, true); } } catch { updateLink(span, '[No] Core', `${CORE_FALLBACK}${encodeURIComponent(doi)}`, true); } } async function checkEuropePMC(doi, span) { const apiUrl = `${EUROPEPMC_API_BASE}${EUROPEPMC_API_QS}${encodeURIComponent(doi)}${EUROPEPMC_API_FMT}`; try { const res = await httpRequest({ method: 'GET', url: apiUrl }); const data = JSON.parse(res.responseText); const results = data?.resultList?.result || []; const result = results.find(r => r.doi?.toLowerCase() === doi.toLowerCase()); if (result && result.isOpenAccess === 'Y' && result.fullTextIdList?.fullTextId?.length) { const accid = result.fullTextIdList.fullTextId[0]; const pdfUrl = `https://europepmc.org/backend/ptpmcrender.fcgi?accid=${accid}&blobtype=pdf`; updateLink(span, '[PDF] EuropePMC', pdfUrl); return; } const fullTextObjs = result?.fullTextIdList?.fullTextId; if (Array.isArray(fullTextObjs)) { const pdfObj = fullTextObjs.find(obj => obj.documentStyle === 'pdf' && obj.url); if (pdfObj?.url) { updateLink(span, '[PDF] EuropePMC', pdfObj.url); return; } } updateLink(span, '[No] EuropePMC', `${EUROPEPMC_SEARCH}${encodeURIComponent(doi)}`, true); } catch { updateLink(span, '[No] EuropePMC', `${EUROPEPMC_SEARCH}${encodeURIComponent(doi)}`, true); } } async function processEntry(result) { const titleLink = result.querySelector('.gs_rt a'); if (!titleLink) return; let buttonContainer = result.querySelector('.gs_or_ggsm'); if (!buttonContainer) { const div = document.createElement('div'); div.className = 'gs_ggs gs_fl'; div.innerHTML = '<div class="gs_ggsd"><div class="gs_or_ggsm"></div></div>'; result.insertBefore(div, result.firstChild); buttonContainer = div.querySelector('.gs_or_ggsm'); } if (buttonContainer.classList.contains('scihub-processed')) return; buttonContainer.classList.add('scihub-processed'); const findBtn = document.createElement('button'); findBtn.textContent = 'Find PDFs'; findBtn.style.color = 'black'; findBtn.style.fontSize = '14px'; buttonContainer.appendChild(findBtn); findBtn.addEventListener('click', async () => { findBtn.remove(); const row1 = document.createElement('span'); row1.style.display = 'inline-flex'; row1.style.gap = '6px'; const scihubSpan = addLoadingIndicator(row1); const libgenSpan = addLoadingIndicator(row1); const row2 = document.createElement('span'); row2.style.display = 'inline-flex'; row2.style.gap = '6px'; const annaSpan = addLoadingIndicator(row2); const scinetSpan = addLoadingIndicator(row2); const row3 = document.createElement('span'); row3.style.display = 'inline-flex'; row3.style.gap = '6px'; const semanticSpan = addLoadingIndicator(row3); const unpaywallSpan = addLoadingIndicator(row3); const row4 = document.createElement('span'); row4.style.display = 'inline-flex'; row4.style.gap = '6px'; const coreSpan = addLoadingIndicator(row4); const europepmcSpan = addLoadingIndicator(row4); [row1, row2, row3, row4].forEach(r => buttonContainer.appendChild(r)); const doi = await fetchDOI(titleLink); checkLibgen(titleLink.textContent, doi, libgenSpan); checkSciHub(titleLink.href, doi, scihubSpan); checkSemanticScholar(titleLink.textContent, semanticSpan, doi); if (doi) { checkAnna(doi, annaSpan); checkSciNet(doi, scinetSpan); checkUnpaywall(doi, unpaywallSpan); checkCore(doi, coreSpan); checkEuropePMC(doi, europepmcSpan); } else { [annaSpan, scinetSpan, unpaywallSpan, coreSpan, europepmcSpan].forEach(span => updateLink(span, '[No] Source', '#', true)); } }); } async function addButtons() { const results = document.querySelectorAll('#gs_res_ccl_mid .gs_r.gs_or.gs_scl'); for (const result of results) await processEntry(result); } addButtons(); new MutationObserver(() => addButtons()).observe(document.body, { childList: true, subtree: true });
