Client vs. Server
Whether a web page is rendered server-side or the client-side matters to SEO. In fact, it’s one of the central issues. Server-side rendering is how content was traditionally delivered — you click on a link, the browser requests the page from the web server, and the server crunches the code to deliver the page in full to your browser.
As pages have become more complex, that work is increasingly done by the browser — the client side. Client-side rendering saves server resources, leading to faster web pages. Unfortunately, it can hurt search-engine friendliness.
This crawl-now-render-later phenomenon creates a delay. “If you have a large dynamic website, then the new content might take a while to be indexed,” according to Mueller.
That means a delay of days or weeks — depending on how much authority your site has — in which the search engines see no content or links on your site. At that point, your rankings and organic search traffic drop, unless you’re using some form of prerendering technology.
Internal links are critical for search engines to discover pages and assign authority. But unless those pages contain both an anchor tag and an href attribute, Google will not consider it a link and will not crawl it.
Span tags do not create crawlable links. Anchor tags with onclick attributes but no href attributes do not create crawlable links.
“At Google, we only analyze one thing: anchor tags with href attributes and that’s it,” according to Greenaway.
In short, modern, complex ecommerce sites should assume that search engines will have trouble indexing.
Organic search is the primary source of customer acquisition for most online businesses. But it’s vulnerable. A website is one technical change away from shutting off the flow — i.e., it “might take a while.” The stakes are too high.