Sign language

videos.json holds sign-language clips. Unlike the other sidecars, its keys are page indexes; use the section id embedded in the filename to match it to the current document’s data-section-id.

{
  "video-1": "sl_pg001_sec001.mp4"
}

const sectionId = fileName
  .replace(/^sl_/, "")
  .replace(/\.(mp4|webm)$/, "");

Compare that id with the page you are displaying. There is no need to reproduce the exporter’s page indexing.

In V1, the keys are video-<pageIndex> and filenames use sl_<sectionId>.mp4 or sl_<sectionId>.webm. Treat a missing key, an unexpected filename, or an unavailable asset as no clip for that page.

Choose a reader-owned surface

Sign-language clips describe the current page context, so a picture-in-picture player is a good default. Close it when the reader navigates to a page with no clip. Glossary-term videos are separate: they arrive in the individual glossary entry rather than videos.json.