initial-sync.js

self.addEventListener("activate", () => {
  let open = indexedDB.open("books", 1);

  open.onupgradeneeded = evt => {
    let db = open.result;
    if (!db.objectStoreNames.contains("books") || !db.objectStoreNames.contains("syncInfo")) {
      if (!db.objectStoreNames.contains("books")) {
        let bookStore = db.createObjectStore("books", { keyPath: "_id" });
        bookStore.createIndex("imgSync", "imgSync", { unique: false });
      }
      if (!db.objectStoreNames.contains("syncInfo")) {
        db.createObjectStore("syncInfo", { keyPath: "id" });
        evt.target.transaction
          .objectStore("syncInfo")
          .add({ id: 1, lastImgSync: null, lastImgSyncStarted: null, lastLoadStarted: +new Date(), lastLoad: null });
      }
      evt.target.transaction.oncomplete = fullSync;
    }
  };
});