IDBDatabase: versionchange event - Web APIs 编辑

The versionchange event is fired when a database structure change (IDBOpenDBRequest.onupgradeneeded event or IDBFactory.deleteDatabase) was requested.

Examples

This example opens a database and, on success, adds a listener to versionchange:

// Open the database
const dBOpenRequest = window.indexedDB.open('Nonexistent', 4);

dBOpenRequest.onupgradeneeded = event => {
  const db = event.target.result;
  // 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.addEventListener('success', event => {
  const db = event.target.result;
  db.addEventListener('versionchange', event => {
    console.log('The version of this database has changed');
  });

});

The same example, using the onversionchange event handler property:

// Open the database
const dBOpenRequest = window.indexedDB.open('Nonexistent', 4);

dBOpenRequest.onupgradeneeded = event => {
  const db = event.target.result;
  // 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 => {
  const db = event.target.result;
  db.onversionchange = event => {
    console.log('The version of this database has changed');
  };

};

Browser compatibility

BCD tables only load in the browser

See also

• Using IndexedDB
• onversionchange event handler property