In a discussion, Google’s John Mueller offered guidance to an SEO professional facing issues with canonicals and the implementation of Angular JavaScript.
Within a Reddit thread, the SEO professional stated:
“For thousands of pages on the site, Google is ignoring the canonical link and choosing an incorrect one.”
Mueller explained that when dealing with canonicals, Google considers: “Are these URLs for the same content?”
If the URLs are not for the same content, why might Google assume they are?
Typically, the answer falls into one of two categories:
– They return mostly the same content to Google.
– The URL structure is too complex for Google to efficiently verify, leading to assumptions.
Mueller addressed this issue specifically in the context of JavaScript:
“With JavaScript-based sites, content issues are a common cause: for instance, in a Single Page Application (SPA) setup where the static HTML is mostly identical, and JavaScript must be executed to reveal any unique content, execution issues may make the content appear identical.”
Mueller identified several reasons why JavaScript might not execute properly:
– Unreliable code
– Lack of graceful degradation
– Resources (such as JavaScript files) or server responses (like API requests) blocked by robots.txt
– Excessive time taken to process JavaScript
If Googlebot executes the code correctly, assessed via the mobile-friendly test, speed could still be a concern.
Mueller noted the difficulty in establishing absolute guidelines or cut-off points for speed, as pages seldom load identically on separate tests.
For further advice, Mueller suggested:
“My way of assessing it is to observe how long the mobile-friendly test takes and use web performance testing tools to gauge how long a page takes to load critical content and the resources needed. More resources increase load time for critical content, complicating Google’s indexing process.”
Mueller concluded that Google likely perceives the two pages in question as offering predominantly identical content. This suggests difficulty in identifying unique content on each page due to a high number of requests needed for loading, or slow response times leading to focus on basic HTML instead of JavaScript-loaded content.
To address the issue, Mueller recommended reducing dependencies and latency.
