Technical SEO Checklist for JavaScript Websites
A JavaScript website needs more than a clean browser view to be search-ready. Important content, links, metadata and structured data should exist in the delivered or reliably rendered HTML; routes need correct status and canonical behavior; and every deployment should be verified as a crawler would receive it, not only inside the application.
Rendering and initial HTML
Inspect the response before JavaScript runs. The primary heading, direct answer, essential links, title, description, canonical and relevant structured data should be available through server rendering or prerendering. Client-only insertion creates a weaker and less predictable discovery path.
Crawlability and status codes
Public routes should return useful HTML and a successful status. Removed URLs need direct permanent redirects to the closest replacement. Soft 404s, redirect chains and catch-all responses that claim success for missing content waste crawl attention and obscure errors.
Canonicals and metadata
Each indexable route needs one self-referencing canonical, one title and one description. Open Graph and Twitter tags should describe the same page. Templates must not leave a base description beside a route-specific one.
Internal links and architecture
Use normal anchor links that crawlers can discover. Important pages should be reachable through navigation, contextual content and topic relationships. Avoid linking internally to redirected URLs; update source links when a slug changes.
Structured data
JSON-LD should match visible content and use stable identifiers for the organization, founder and website. Service pages can describe the offered service; articles should emit one BlogPosting; visible breadcrumbs should match BreadcrumbList data; FAQPage is valid only when the exact answers are shown.
Sitemaps and robots
The XML sitemap should list canonical public URLs only and remain synchronized with routing. Robots rules should permit valuable pages while excluding private QA surfaces and irrelevant files. A sitemap cannot compensate for blocked or broken routes.
Core Web Vitals
Reserve image dimensions, prioritize the main visual, defer below-fold media, split non-critical code and prevent font or animation shifts. Test mobile layouts because navigation, wide code blocks and fixed controls commonly create overflow or interaction delays.
Verification after deployment
Run automated checks, then request the final URL and inspect the returned HTML. Validate links, schemas and response behavior, use Search Console URL Inspection when available, and record what changed. A green local build is necessary but not proof of the deployed response.
Frequently asked questions
Does Google render JavaScript?
Often, but rendering can be delayed or fail. Delivering primary content in initial HTML removes unnecessary dependence on that step.
Is prerendering enough for every application?
It works well for known public routes whose content changes at build time. Highly dynamic or personalized pages may need server rendering.
Should every page have FAQ schema?
No. Use it only when useful questions and identical answers are visibly rendered.
Can a SPA return real redirects?
Client routing can navigate, but HTTP-level permanent redirects should be configured on the deployment platform when SEO preservation matters.
What should be checked after every release?
Generated HTML, status behavior, canonicals, sitemap, structured data, images, links and key mobile pages.
Do Core Web Vitals guarantee rankings?
No. They improve experience and technical quality but are only part of search performance.