Definition
JavaScript SEO encompasses the techniques and best practices for ensuring that content generated or modified by JavaScript is properly discovered, crawled, and indexed by search engines. Google uses a two-step process: HTML crawling then JavaScript rendering. This rendering is costly and may be deferred, meaning content generated solely by JavaScript may take longer to be indexed. SPA frameworks (React, Vue, Angular) pose particular challenges that Server-Side Rendering (SSR) or pre-rendering can solve.
Key Points
- Google renders JavaScript but with a potential delay
- SPAs (React, Vue, Angular) require special SEO attention
- SSR or pre-rendering are the recommended solutions
Practical Examples
Unoptimized SPA
A client-side rendered React site has poorly indexed pages because Google doesn't always render JavaScript. Migration to Next.js (SSR) restores full indexation.
Lazy rendering
A site loads its main content via an AJAX call on scroll. Google doesn't see this content during the initial crawl. Including content in the initial HTML solves the problem.
Frequently Asked Questions
Google uses a version of Chrome to render JavaScript, but rendering is costly and deferred. Critical content should not rely solely on JavaScript for fast indexation.
Use the URL Inspection tool in Search Console to see the rendered HTML. Compare the source code (Ctrl+U) with the DOM tree (Inspect) to identify JS-generated content.
Go Further with LemmiLink
Discover how LemmiLink can help you put these SEO concepts into practice.
Last updated: 2026-02-07