Opens External Anchors Using rel="noopener"

Overview

When your page links to another page using target="_blank", the new page runs on the same process as your page. If the new page is executing expensive JavaScript, your page's performance may also suffer.

On top of this, target="_blank" is also a security vulnerability. The new page has access to your window object via window.opener, and it can navigate your page to a different URL using window.opener.location = newURL.

See The Performance Benefits of rel=noopener for more information.

Recommendations

Add rel="noopener" to each of the links that Lighthouse has identified in your report. In general, always add rel="noopener" when you open an external link in a new window or tab.

<a href="https://examplepetstore.com" target="_blank" rel="noopener">...</a>

More information

Lighthouse uses the following algorithm to flag links as rel="noopener" candidates:

  1. Gather all <a> nodes that contain the attribute target="_blank" and do not contain the attribute rel="noopener".
  2. Filter out any same-host links.

Because Lighthouse filters out same-host links, there's an edge case that you might want to be aware of if you're working on a large site. If your page opens a link to another section of your site without using rel="noopener", the performance implications of this audit still apply. However, you won't see these links in your Lighthouse results.

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