This page in question features hyperlinks that become detectable only after JavaScript is executed; these hyperlinks are absent in the server's initial HTML response.
Why is this important?
The process of rendering web pages consumes considerable resources and takes distinctly more time than simply fetching the raw HTML content from the server.
During Google's two-phase crawling process, the initial phase scrutinizes the HTML response, while the second phase involves page rendering and a review of the rendered HTML to refine the index.
As Google crawls a new page, they first analyze the response HTML to extract links for their crawl queue. This occurs prior to the rendering process, implying that hyperlinks missing from the server's response could delay the discovery and indexing of new links by Google.
What does the Optimization check?
This Optimization is activated for any internal URL where hyperlinks appear in the rendered HTML but are missing from the server's response.
Examples that trigger this Optimization
The Optimization will be set off by any URL containing one or more hyperlinks in the rendered HTML that do not exist in the server's response HTML.
For instance, consider the response HTML appears as follows:
<!doctype html><html lang="en"><head> ...</head><body> <h1>This is a page</h1> ...</body></html>
Whereas the rendered HTML could look something like this:
<!doctype html><html lang="en"><head> ...</head><body> <h1>This is a webpage</h1> <a href="https://loudinteractive.com">Dynamic Link</a> ...</body></html>
How do you resolve this issue?
According to Google's guidelines, using JavaScript to generate content, including links, isn't inherently problematic; they plan to render and index every page that can be indexed, eventually updating based on the rendered content.
Hence, if JavaScript is utilized to add links, those links are likely to be discovered by Google at some point. What matters is the nature of these JavaScript-generated links and whether their delayed discovery is acceptable for your SEO strategy.
To delve deeper, you can leverage the Response vs Render report, which identifies differences between the source and rendered content. This tool enables a granular analysis of the links through features such as the 'JavaScript Status' filter within the Link Explorer:
You'll find several conditions categorized as follows:
Created - indicating the link was not in the server's response and is presumed to be generated by JavaScript.
Modified - signifying that the link pre-existed in the response HTML, but JavaScript has since modified its text or destination URL.
No - confirming that JavaScript has neither added nor modified the link.
The Link Explorer provides a means to review data collectively, and if you're keen on focusing on particular URLs or links, you can do so by examining the data on the URL Details page, covering both incoming and outgoing links.
Such JavaScript-generated links will also be apparent in the Links report, displayed in the accompanying data tables.
For isolated evaluations of individual pages, this information is also available via the Single Page Analyser tool.