Add Google Scholar links next to DOIs on any page
// ==UserScript==
// @name DOI to Google Scholar Link
// @namespace http://tampermonkey.net/
// @version 1.3
// @description Add Google Scholar links next to DOIs on any page
// @author Jerry
// @match *://*/*
// @exclude *://scholar.google.com/*
// homepage https://greasyfork.org/en/scripts/563946
// @grant none
// ==/UserScript==
(function() {
'use strict';
// DOI regex patterns
// Pattern 1: Full DOI URLs (https://doi.org/10.xxxx)
const doiURLPattern = /https?:\/\/doi\.org\/(10\.\d{4,}(?:\.\d+)*\/\S+(?:(?![\"&\'<>])\S)*)/gi;
// Pattern 2: DOI text format (doi: 10.xxxx or doi:10.xxxx)
const doiTextPattern = /\b(?:doi|DOI)\s*:\s*(10\.\d{4,}(?:\.\d+)*\/\S+(?:(?![\"&\'<>])\S)*)/gi;
// Function to create Scholar link
function createScholarLink(doi) {
const link = document.createElement('a');
link.href = `https://scholar.google.com/scholar?q=${encodeURIComponent(doi)}`;
link.textContent = ' 🎓';
link.title = 'Search in Google Scholar';
link.target = '_blank';
link.style.textDecoration = 'none';
link.style.marginLeft = '4px';
return link;
}
// Function to process text nodes for plain text DOI URLs and DOI text
function processTextNode(node) {
const text = node.textContent;
// Find all matches from both patterns
const urlMatches = [...text.matchAll(doiURLPattern)];
const textMatches = [...text.matchAll(doiTextPattern)];
// Combine and sort matches by position
const allMatches = [...urlMatches, ...textMatches].sort((a, b) => a.index - b.index);
if (allMatches.length === 0) return;
const parent = node.parentNode;
if (!parent || parent.tagName === 'SCRIPT' || parent.tagName === 'STYLE') return;
// Skip if parent is a link (anchor tag)
if (parent.tagName === 'A') return;
let lastIndex = 0;
const fragment = document.createDocumentFragment();
allMatches.forEach(match => {
const fullMatch = match[0];
const doi = match[1];
const startIndex = match.index;
// Skip overlapping matches
if (startIndex < lastIndex) return;
// Add text before DOI
if (startIndex > lastIndex) {
fragment.appendChild(document.createTextNode(text.substring(lastIndex, startIndex)));
}
// Add DOI text/URL
fragment.appendChild(document.createTextNode(fullMatch));
// Add Scholar link
fragment.appendChild(createScholarLink(doi));
lastIndex = startIndex + fullMatch.length;
});
// Add remaining text
if (lastIndex < text.length) {
fragment.appendChild(document.createTextNode(text.substring(lastIndex)));
}
parent.replaceChild(fragment, node);
}
// Function to process anchor elements with DOI links
function processAnchor(anchor) {
// Skip if already has a scholar link after it
if (anchor.nextSibling?.textContent?.includes('🎓')) return;
const href = anchor.href;
// Check if it's a DOI link (https://doi.org/10.xxxx/...)
if (href && href.includes('doi.org/10.')) {
const match = href.match(/10\.\d{4,}(?:\.\d+)*\/\S+/);
if (match) {
const doi = match[0];
const scholarLink = createScholarLink(doi);
anchor.parentNode.insertBefore(scholarLink, anchor.nextSibling);
}
}
}
// Walk through all text nodes and anchor elements
function processPage() {
// Process text nodes for plain text DOI URLs
const walker = document.createTreeWalker(
document.body,
NodeFilter.SHOW_TEXT,
{
acceptNode: function(node) {
// Skip script, style, and already processed nodes
if (node.parentNode.tagName === 'SCRIPT' ||
node.parentNode.tagName === 'STYLE' ||
node.textContent.includes('🎓')) {
return NodeFilter.FILTER_REJECT;
}
return NodeFilter.FILTER_ACCEPT;
}
}
);
const textNodes = [];
let currentNode;
while (currentNode = walker.nextNode()) {
textNodes.push(currentNode);
}
textNodes.forEach(processTextNode);
// Process anchor elements with DOI links
document.querySelectorAll('a[href*="doi.org/10."]').forEach(processAnchor);
}
// Run on page load
if (document.readyState === 'loading') {
document.addEventListener('DOMContentLoaded', processPage);
} else {
processPage();
}
// Watch for dynamic content
const observer = new MutationObserver(mutations => {
mutations.forEach(mutation => {
mutation.addedNodes.forEach(node => {
if (node.nodeType === Node.ELEMENT_NODE) {
// Process new text nodes
const walker = document.createTreeWalker(
node,
NodeFilter.SHOW_TEXT,
null
);
let textNode;
while (textNode = walker.nextNode()) {
if (!textNode.textContent.includes('🎓')) {
processTextNode(textNode);
}
}
// Process new anchor elements
if (node.tagName === 'A' && node.href && node.href.includes('doi.org/10.')) {
processAnchor(node);
}
node.querySelectorAll('a[href*="doi.org/10."]').forEach(processAnchor);
}
});
});
});
observer.observe(document.body, {
childList: true,
subtree: true
});
})();