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

IDBVersionChangeEventEvent 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");
  };
};
```

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* Using IndexedDB