I spent 5 hours debugging why Google couldn't see my React app. The fix was 4 lines of code. Not a webpack config. Not a server migration. Four. Lines. That afternoon taught me more about JavaScript SEO than any blog post I'd read. If you're building modern frontends with React, understanding React SEO is no longer optional. If you're shipping SPAs, Next.js apps, or anything that leans on client-side rendering and you care about organic traffic, this checklist is for you. Let's go through the real issues and the actual fixes. 1. Understand How Googlebot Actually Renders Your JS Here's the counterintuitive part most developers miss: Googlebot renders JavaScript, but not instantly. Google uses a two-wave indexing model. The first wave crawls your raw HTML. The second wave which may come days or weeks later renders the JavaScript and indexes the dynamic content. If your critical content only exists after JS executes, you're invisible to Google's first pass.…