IDBOpenDBRequest: blocked event

The blocked handler is executed when an open connection to a database is blocking a versionchange transaction on the same database.

This event is not cancelable and does not bubble.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

js
addEventListener("blocked", (event) => {});

onblocked = (event) => {};

Event type

An IDBVersionChangeEvent. Inherits from Event.

Event IDBVersionChangeEvent

Event properties

Also inherits properties from its parent, Event interface.

IDBVersionChangeEvent.oldVersion Read only

Returns the old version of the database.

IDBVersionChangeEvent.newVersion Read only

Returns the new version of the database.

Examples

Using addEventListener():

js
// Open the database
const DBOpenRequest = window.indexedDB.open("toDoList", 4);

DBOpenRequest.onupgradeneeded = (event) => {
  const db = event.target.result;

  db.onerror = () => {
    console.log("Error creating database");
  };

  // Create an objectStore for this database
  const 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 });
};

DBOpenRequest.onsuccess = (event) => {
  // Let's try to open the same database with a higher revision version
  const req2 = indexedDB.open("toDoList", 5);

  // In this case the onblocked handler will be executed
  req2.addEventListener("blocked", () => {
    console.log("Request was blocked");
  });
};

Using the onblocked property:

js
// Open the database
const DBOpenRequest = window.indexedDB.open("toDoList", 4);

DBOpenRequest.onupgradeneeded = (event) => {
  const db = event.target.result;

  db.onerror = () => {
    console.log("Error creating database");
  };

  // Create an objectStore for this database
  const 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 });
};

DBOpenRequest.onsuccess = (event) => {
  // Let's try to open the same database with a higher revision version
  const req2 = indexedDB.open("toDoList", 5);

  // In this case the onblocked handler will be executed
  req2.onblocked = () => {
    console.log("Request was blocked");
  };
};

Specifications

Specification
Indexed Database API 3.0
# eventdef-idbopendbrequest-blocked

Browser compatibility

BCD tables only load in the browser

See also