IDBOpenDBRequest: blocked event

{{APIRef("IndexedDB")}} 

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 {{domxref("EventTarget.addEventListener", "addEventListener()")}} , or set an event handler property.

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

onblocked = (event) => {};

Event type

An {{domxref("IDBVersionChangeEvent")}} . Inherits from {{domxref("Event")}} .

{{InheritanceDiagram("IDBVersionChangeEvent")}} 

Event properties

Also inherits properties from its parent, {{domxref("Event")}}  interface.

• {{ domxref("IDBVersionChangeEvent.oldVersion") }}  {{ReadOnlyInline}} 
  • : Returns the old version of the database.
• {{ domxref("IDBVersionChangeEvent.newVersion") }}  {{ReadOnlyInline}} 
  • : Returns the new version of the database.

Examples

Using addEventListener():

// 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:

// 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

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Using IndexedDB