IDBTransaction: error property

BaselineWidely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

* Some parts of this feature may have varying levels of support.

Note: This feature is available inWeb Workers.

TheIDBTransaction.error property of theIDBTransaction interfacereturns the type of error when there is an unsuccessful transaction.

Value

ADOMException containing the relevant error, ornull if there are none.

It can be a reference to the same error as the request object that raised it, or a transactionfailure (for exampleQuotaExceededError).

This property isnull if the transaction is not finished, or is finished andwas successfully committed.

In the following code snippet, we open a read/write transaction on our database and addsome data to an object store. Note also the functions attached to transaction eventhandlers to report on the outcome of the transaction opening in the event of success orfailure. Note thetransaction.onerror = (event) => { }; block, makinguse oftransaction.error to help in reporting what went wrong when thetransaction was unsuccessful. For a full working example, see ourTo-do Notifications app (View example live).

const note = document.getElementById("notifications");// an instance of a db object for us to store the IDB data inlet db;// Let us open our databaseconst DBOpenRequest = window.indexedDB.open("toDoList", 4);DBOpenRequest.onsuccess = (event) => {  note.appendChild(document.createElement("li")).textContent =    "Database initialized.";  // store the result of opening the database in the db variable.  // This is used a lot below  db = DBOpenRequest.result;  // Run the addData() function to add the data to the database  addData();};function addData() {  // Create a new object ready for being inserted into the IDB  const newItem = [    {      taskTitle: "Walk dog",      hours: 19,      minutes: 30,      day: 24,      month: "December",      year: 2013,      notified: "no",    },  ];  // open a read/write db transaction, ready for adding the data  const transaction = db.transaction(["toDoList"], "readwrite");  // report on the success of opening the transaction  transaction.oncomplete = (event) => {    note.appendChild(document.createElement("li")).textContent =      "Transaction completed: database modification finished.";  };  transaction.onerror = (event) => {    note.appendChild(document.createElement("li")).textContent =      `Transaction not opened due to error: ${transaction.error}`;  };  // create an object store on the transaction  const objectStore = transaction.objectStore("toDoList");  // add our newItem object to the object store  const objectStoreRequest = objectStore.add(newItem[0]);  objectStoreRequest.onsuccess = (event) => {    // report the success of the request (this does not mean the item    // has been stored successfully in the DB - for that you need transaction.onsuccess)    note.appendChild(document.createElement("li")).textContent =      "Request successful.";  };}