Indexed Database API 3.0

The following example uses the API to access a "library" database. It has a "books" object store that holds books records stored by their "isbn" property as the primary key.

Book records have a "title" property. This example artificially requires that book titles are unique. The code enforces this by creating an index named "by_title" with the unique option set. This index is used to look up books by title, and will prevent adding books with non-unique titles.

Book records also have an "author" property, which is not required to be unique. The code creates another index named "by_author" to allow look-ups by this property.

The code first opens a connection to the database. The upgradeneeded event handler code creates the object store and indexes, if needed. The success event handler code saves the opened connection for use in later examples.

const request = indexedDB.open("library");
let db;

request.onupgradeneeded = function() {
  // The database did not previously exist, so create object stores and indexes.
  const db = request.result;
  const store = db.createObjectStore("books", {keyPath: "isbn"});
  const titleIndex = store.createIndex("by_title", "title", {unique: true});
  const authorIndex = store.createIndex("by_author", "author");

  // Populate with initial data.
  store.put({title: "Quarry Memories", author: "Fred", isbn: 123456});
  store.put({title: "Water Buffaloes", author: "Fred", isbn: 234567});
  store.put({title: "Bedrock Nights", author: "Barney", isbn: 345678});
};

request.onsuccess = function() {
  db = request.result;
};

The following example populates the database using a transaction.

const tx = db.transaction("books", "readwrite");
const store = tx.objectStore("books");

store.put({title: "Quarry Memories", author: "Fred", isbn: 123456});
store.put({title: "Water Buffaloes", author: "Fred", isbn: 234567});
store.put({title: "Bedrock Nights", author: "Barney", isbn: 345678});

tx.oncomplete = function() {
  // All requests have succeeded and the transaction has committed.
};

The following example looks up a single book in the database by title using an index.

const tx = db.transaction("books", "readonly");
const store = tx.objectStore("books");
const index = store.index("by_title");

const request