index.js

let db;
let version = 2;
const request = indexedDB.open("database", version);
request.onerror = function(event) {
  alert("IndexedDB が使えません");
};
request.onupgradeneeded = function(event) {
  let txn = event.target.transaction;
  debugger;
  const objectStore = txn.objectStore("items", { keyPath: "id" });
  objectStore.name = 'products';
  const index = objectStore.index('name');
  index.name = 'title';
};
request.onsuccess = function(event) {
  db = event.target.result;
}