The URL in focus has an <h1> element that is not consistent between the initial HTML response of the page and the final rendered HTML.
Why is this important?
The process of rendering webpages demands significant resources and is more time-consuming compared to simply retrieving the base HTML content.
Google typically performs a two-stage crawling process: initially examining the HTML response, then rendering the page for a more in-depth look at the fully rendered HTML, after which the index is updated to reflect the content found in the rendered page.
Therefore, URLs generally enter Google's index based on the preliminary crawl, with a lag before the second crawl takes place. The HTML response must contain all the vital features, precisely reflecting what should be indexed, especially the page title.
If the <h1> is dynamically altered through JavaScript, this means that it's the rendered HTML's <h1> that holds the correct title. Yet, Google might index the page with the <h1> from the HTML response, and updating this can take time.
This issue becomes particularly problematic if the page content or <h1> frequently changes, as Google might index an outdated version.
What does the Optimization check?
The hint is triggered for any internal URL where the <h1> tag in the response HTML differs from that in the rendered HTML.
Examples that trigger this Optimization
The hint activates for any URL where there's an incongruity between the <h1> in the response and rendered HTML.
For instance, if the response HTML is as follows:
<!doctype html><html lang="en"><head> ...</head><body> <h1>My Teenage Years</h1> ...</body></html>
And if the rendered HTML appears like this:
<!doctype html><html lang="en"><head> ...</head><body> <h1>Reminiscing My Youth</h1> ...</body></html>
How do you resolve this issue?
Reliance on JavaScript for fundamental page components isn't recommended, as it might lead to incorrect or delayed indexing. Google's ability to render or execute JavaScript may not be flawless.
The <h1> tag is a vital SEO element that should be clearly present and optimized when Google initially crawls the page.
To rectify this, collaboration with your development team is essential to guarantee that the proper <h1> is part of the HTML response and remains unchanged through the rendering process.