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seo/json-ld-date-format · JSON-LD date format

Date properties in JSON-LD should be ISO-8601.

Severity: info

What it checks

Flags a value under a known date key (datePublished, dateModified, startDate, …) that is not ISO-8601. Reduced precision allowed by schema.org is accepted: year (2026), year-month (2026-06), full date, and date-time all pass.

Why it matters

Schema.org date properties expect ISO-8601; other formats may be ignored or misparsed.

How to fix

"datePublished": "2026-06-26"

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 known meta components (svelte-meta-tags, svelte-seo) and any you declare in metaComponents. It judges only a literal value; it never examines a dynamic one. Rendered analysis (the Vite plugin’s build pass, a route you visit in the dashboard) reads the shipped <head>, where every value is literal; 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-date-format': 'off'
  }
};