seo/json-ld · JSON-LD structured data

Every route should include JSON-LD structured data.

Severity: info

What it checks

Every route should include a <script type="application/ld+json"> JSON-LD block (own or inherited through the layout chain), in <head> or <body>. A missing JSON-LD block is flagged.

Why it matters

JSON-LD structured data lets search engines render rich results (breadcrumbs, articles, products) for the page.

How to fix

Add a JSON-LD <script> inside <svelte:head> with literal JSON. Svelte emits the script body as-is, so an interpolation like {JSON.stringify(...)} would be emitted as that literal string and produce invalid JSON-LD:

<svelte:head>
  <script type="application/ld+json">
    {
      "@context": "https://schema.org",
      "@type": "WebPage",
      "name": "Page title"
    }
  </script>
</svelte:head>

Mode differences

Source analysis (the CLI, the dashboard’s static baseline) composes each route’s <head> from <svelte:head> in the page and its layout chain, followed into repo-local components, plus the tags in src/app.html’s <head>, the known meta components (svelte-meta-tags, svelte-seo, svead) and any you declare in metaComponents. A value it cannot read literally ({data.title}) is dynamic, judged by treatDynamicAs. A component a function mounts with import() renders only in the browser: its JSON-LD counts on a route with ssr = false, and not on a server-rendered route, whose HTML has none. JSON-LD counts wherever the document carries it, in <body> as well as <head>; one the body renders counts as a dynamic block. JSON-LD injected with {@html} is not a <script> element source analysis can see, so it counts as a dynamic JSON-LD block only when the expression’s source text names it (jsonld, json-ld, ld+json or structured data, e.g. {@html serializeJsonLd(data)}), or the expression is a script binding whose initializer builds a tag with type="application/ld+json" or calls a function named for JSON-LD (jsonLd(data)), directly or from another such binding, or the item of an {#each} over a list the source names for JSON-LD ({#each jsonLdScripts as script}, {#each structuredData as ld}); any other {@html} reports Missing there, while rendered analysis finds it. A block under a condition ({#if ld}{@html ld}{/if}) counts as present on every route that renders its component. Rendered analysis (the Vite plugin’s build pass, a route you visit in the dashboard) reads the shipped <head>, and the JSON-LD in <body>, where every value is literal and treatDynamicAs does not apply; the build pass covers prerendered routes only. When the two disagree, trust the rendered result.

Disabling

Record existing findings in the suppressions file (npx svelte-vitals --update-suppressions), scope the rule per route or path with overrides, or turn it off:

export default {
  rules: {
    'seo/json-ld': 'off'
  }
};