The clear() method of the IDBObjectStore interface creates and immediately returns an IDBRequest object, and clears this object store in a separate thread. This is for deleting all the current data out of an object store. 
  Clearing an object store consists of removing all records from the object store and removing all records in indexes that reference the object store. To remove only some of the records in a store, use IDBObjectStore.delete passing a key or IDBKeyRange. 
 
An IDBRequest object on which subsequent events related to this operation are fired.
 If the operation is successful, the value of the request's result property is undefined.
 
 In the following code snippet, we open a read/write transaction on our database and clear all the current data out of the object store using clear(). For a full working example, see our To-do Notifications app (view example live). 
 
const DBOpenRequest = window.indexedDB.open("toDoList", 4);
DBOpenRequest.onsuccess = (event) => {
  note.innerHTML += "<li>Database initialized.</li>";
  
  
  db = DBOpenRequest.result;
  
  clearData();
};
function clearData() {
  
  const transaction = db.transaction(["toDoList"], "readwrite");
  
  transaction.oncomplete = (event) => {
    note.innerHTML += "<li>Transaction completed.</li>";
  };
  transaction.onerror = (event) => {
    note.innerHTML += `<li>Transaction not opened due to error: ${transaction.error}</li>`;
  };
  
  const objectStore = transaction.objectStore("toDoList");
  
  const objectStoreRequest = objectStore.clear();
  objectStoreRequest.onsuccess = (event) => {
    
    note.innerHTML += "<li>Request successful.</li>";
  };
}