Javascript SEO: How Google Crawls, Renders & Indexes JS

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This post details research conducted in partnership with MERJ to empirically demystify Google's crawling and rendering of JavaScript-heavy websites. It presents findings from analyzing over 100,000 Googlebot fetches, focusing on the evolution of Google's rendering capabilities and debunking common myths. Key contributions include: 1) Demonstrating that 100% of analyzed HTML pages on nextjs.org resulted in full-page renders by Googlebot, including complex JS interactions and dynamically loaded content via API calls and RSCs. 2) Validating that Google treats JavaScript-heavy pages similarly to static HTML pages in terms of indexing and processing. 3) Providing evidence that rendering queue and timing, and page discovery speed for JS-heavy sites, are not significantly impacted as previously believed. The methodology involved custom Edge Middleware for data collection and analysis of server access logs against rendering beacons.