indexedDB.js

let openRequest = indexedDB.open("mystore", 3);

openRequest.onupgradeneeded = function(event) {
   let db = openRequest.result;
  switch(event.oldVersion) { // existing db version
    case 1:
      // do changes for update from version 1 to 3...
         db.createObjectStore("books",{autoIncrement:true});
    case 2:
      // do changes for update from version 2 to 3...
         let booksStore=openRequest.transaction.objectStore("books");
         books.createIndex("name","book_name",{unique:false});
         db.createObjectStore("users",{autoIncrement:true});
  }
};

openRequest.onerror = function() {
  console.error("Error", openRequest.error);
};

openRequest.onsuccess = function() {
  let db = openRequest.result;
   
};