DOM

次のコードスニペットでは、データベースを非同期で開き（IDBFactory）、成功と失敗の場合にイベントを登録し、アップグレードが必要な場合には、新しいオブジェクト ストアを生成しています（IDBdatabase）。完璧に動作する例は、To-do Notifications app（view example live.）を見てください。

// Let us open our database
  var DBOpenRequest = window.indexedDB.open("toDoList", 4);

  // these two event handlers act on the IDBDatabase object, when the database is opened successfully, or not
  DBOpenRequest.onerror = function(event) {
    note.innerHTML += '<li>Error loading database.</li>';
  };

  DBOpenRequest.onsuccess = function(event) {
    note.innerHTML += '<li>Database initialised.</li>';

    // store the result of opening the database in the db variable. This is used a lot later on
    db = DBOpenRequest.result;

    // Run the displayData() function to populate the task list with all the to-do list data already in the IDB
    displayData();
  };

  // This event handles the event whereby a new version of the database needs to be created
  // Either one has not been created before, or a new version number has been submitted via the
  // window.indexedDB.open line above

  DBOpenRequest.onupgradeneeded = function(event) {
    var db = event.target.result;

    db.onerror = function(event) {
      note.innerHTML += '<li>Error loading database.</li>';
    };

    // Create an objectStore for this database using IDBDatabase.createObjectStore

    var objectStore = db.createObjectStore("toDoList", { keyPath: "taskTitle" });

    // define what data items the objectStore will contain

    objectStore.createIndex("hours", "hours", { unique: false });
    objectStore.createIndex("minutes", "minutes", { unique: false });
    objectStore.createIndex("day", "day", { unique: false });
    objectStore.createIndex("month", "month", { unique: false });
    objectStore.createIndex("year", "year", { unique: false });

    objectStore.createIndex("notified", "notified", { unique: false });

    note.innerHTML += '<li>Object store created.</li>';
  };

次の行は、データベースでトランザクションを開いて、そしてオブジェクト ストアを開いて、内側のデータを操作しています。

    var objectStore = db.transaction('toDoList').objectStore('toDoList');