Find duplicate IDs
Scans the page for repeated id attributes, highlights them and reports the occurrence count to the console.
Code to copy
try {
const seen = {};
const dupes = {};
document.querySelectorAll('[id]').forEach(function (el) {
const id = el.id;
if (seen[id]) {
dupes[id] = (dupes[id] || 1) + 1;
el.style.outline = '3px solid #CC241D';
} else {
seen[id] = true;
}
});
const keys = Object.keys(dupes);
if (keys.length) {
console.warn('JustZix: duplicate IDs found:', dupes);
} else {
console.log('JustZix: no duplicate IDs');
}
} catch (err) { console.error('JustZix duplicate IDs:', err); }How to use this example
- Copy the code with the button above.
- Install JustZix (2 minutes) and open the extension on the target page.
- Add a new rule matching that page.
- Paste the code into the rule's JavaScript panel and save — it runs on every page visit.
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