There was a terrific post from Vercel’s blog How Google handles JavaScript throughout the indexing process. The short version of this post is yes, the Google indexer/spider can read content loaded through Javascript. That should come as no surprise to most professional SEO-ers out there, but it’s always worth a reminder. I did want to highlight one or possibly two important items in the recommendations section.
Critical SEO elements: Use server-side rendering or static generation for critical SEO tags and important content to ensure they’re present in the initial HTML response.
https://vercel.com/blog/how-google-handles-javascript-throughout-the-indexing-process
Content updates: For content that needs to be quickly re-indexed, ensure changes are reflected in the server-rendered HTML, not just in client-side JavaScript. Consider strategies… to balance content freshness with SEO and performance.
https://vercel.com/blog/how-google-handles-javascript-throughout-the-indexing-process
Yes, the Google spider can read Javascript. At the same time, there are tradeoffs to be considered, such as if scripting is slow loading the content, then the spider “sees” your page as being slow and possibly annoying to the user.
My thoughts are: if you’re scroll-loading/infinite scrolling content (i.e. the user scrolls down the page and more posts/images/whatever keep appearing) don’t assume that the Google spider is going to keep scrolling down forever. Your site should have an alternative way to link to those posts/images, such as through a tags or categories section, or through a calendar widget like the one on learngoogle.com’s home page. Have a sitemap so Google’s spider isn’t reliant on having to use Javascript to see all of your pages. Make sure that any scripts loading content run fast, and are not heavily changing the layout of the page.