Google Explains Extra About Head Part & JavaScript

Last week we reported on a comment made by John Mueller of Google about the head section of your HTML and why you should keep it clean. John, on Friday, posted a mastodon thread explaining more about the head section and how search engines interact with it, especially if there is a lot of JavaScript in it.

Here is the content from the thread:

SEO in your head vs too much #JavaScript?

This comes up from time to time, I thought I’d be more elaborate once (it’s not new). Search engines (I only really know Google, YMMV) render HTML pages and there are some settings that need to be found in the head of a page in order to be valid. If you care about these settings, don’t make them

brittle, and ideally move those settings to the top of the head.

The SEO settings I’m thinking of are the robots meta tag & the canonical link element, but there’s also the title & description meta tag which some people consider important. It’s not just about SEO either – you probably also want to make sure things like the character set definition, viewport & CSP are considered valid.

“Of course my head is ok” – sometimes it’s not as obvious as clearly broken markup. The head is self-closing, so any HTML element that’s not valid in the

will result in the rest to be considered as a part of the body. That can be a stray img that ends up somewhere wrong, it could be an iframe that a script injects to the top of the head during rendering. This is visible if you inspect the DOM of a page in your browser.

Browsers are sometimes helpful and try to interpret what you mean, if you don’t want a page to be indexed, or want a different URL as canonical, you probably don’t want search engines to guess. (SEO is to a large part about not making search engines guess.)

In short, avoid making the head brittle if you care about those SEO settings, consider moving them to the top of the head (don’t include 5k lines of JS above them), and double-check the rendered DOM in your browser from time to time.

You don’t have to move it into the body (that can cause other problems), I’d move it to below the critical elements that you need to have discovered in the head.

— John Mueller is mostly not here 🐀 (@JohnMu) January 13, 2023

That is the end of his head thread – got it?

Forum discussion at mastodon.