The IDBOpenDBRequest interface of the IndexedDB API provides access to the results of requests to open or delete databases (performed using IDBFactory.open and IDBFactory.deleteDatabase), using specific event handler attributes.
Fired when an attempt was made to open a database with a version number higher than its current version. Also available via the onupgradeneeded property.
Example
In the following example you can see the onupgradeneeded handler being used to update the database structure if a database with a higher version number is loaded. For a full working example, see our To-do Notifications app (view example live.)
js
let db;// Let us open our databaseconst DBOpenRequest = window.indexedDB.open("toDoList",4);// these event handlers act on the database being opened.
DBOpenRequest.onerror=(event)=>{
note.innerHTML +="<li>Error loading database.</li>";};
DBOpenRequest.onsuccess=(event)=>{
note.innerHTML +="<li>Database initialized.</li>";// store the result of opening the database in the db// variable. This is used a lot below
db = DBOpenRequest.result;// Run the displayData() function to populate the task// list with all the to-do list data already in the IDBdisplayData();};// This event handles the event whereby a new version of// the database needs to be created Either one has not// been created before, or a new version number has been// submitted via the window.indexedDB.open line above// it is only implemented in recent browsers
DBOpenRequest.onupgradeneeded=(event)=>{const db = event.target.result;
db.onerror=(event)=>{
note.innerHTML +="<li>Error loading database.</li>";};// Create an objectStore for this databaseconst 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});
objectStore.createIndex("notified","notified",{unique:false});};