Important: As of Firefox 52, the property defined in this mixin has been moved to the WindowOrWorkerGlobalScope mixin, and other browsers will follow suit. Look to that page for up-to-date details.
The IDBEnvironment helper of the IndexedDB API contains the indexedDB property, which provides access to IndexedDB functionality. It is the top level IndexedDB interface implemented by the window and Worker objects.
IDBEnvironment.indexedDB Read only 
IDBFactory object.The following code creates a request for a database to be opened asychronously, after which the database is opened when the request's onsuccess handler is fired:
var db;
function openDB() {
 var DBOpenRequest = window.indexedDB.open("toDoList");
 DBOpenRequest.onsuccess = function(e) {
   db = DBOpenRequest.result;
 };
}
 | Specification | Status | Comment | 
|---|---|---|
| Indexed Database API The definition of 'IDBEnvironment' in that specification.  |  Recommendation | 
| Desktop | ||||||
|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
| Basic support |  24
  | 
Yes |  16
  | 
 10
  | 
15 | 7 | 
| Available in workers | Yes | Yes | 37 | ? | Yes | ? | 
| Mobile | |||||||
|---|---|---|---|---|---|---|---|
| Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
| Basic support | Yes | 25 | ? | 22 | 22 | 8 | Yes | 
| Available in workers | Yes | Yes | Yes | 37 | Yes | ? | Yes | 
IDBDatabase
IDBTransaction
IDBKeyRange
IDBObjectStore
IDBCursor
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    https://developer.mozilla.org/en-US/docs/Web/API/IDBEnvironment