This presentation explores how On, a global sports brand, tackles the challenges of crawling, rendering, and indexing JavaScript-heavy websites. It highlights the importance of strategic URL management, the pitfalls of JavaScript redirects, and introduces solutions like Server-Side Rendering (SSR) and Dynamic Rendering to improve SEO performance. Key benefits and drawbacks of dynamic rendering are discussed, alongside a practical demonstration of Chrome Dev Tools for testing. Ultimately, it provides actionable insights for maintaining visibility and SEO success in the JavaScript-driven web environment.