minor fixes

Author: iliakan

6-data-storage/03-indexeddb/article.md

@@ -131,9 +131,7 @@ In order to organize that, the `versionchange` event triggers on the "outdated"
 
 If we don't listen for the `versionchange` event and don't close the old connection, then the second, new connection won't be made. The `openRequest` object will emit the `blocked` event instead of `success`. So the second tab won't work.
 
-Here's the code to correctly handle the parallel upgrade.
-
-It installs an `onversionchange` handler after the database is opened, that closes the old connection:
+Here's the code to correctly handle the parallel upgrade. It installs the `onversionchange` handler, that triggers if the current database connection becomes outdated (db version is updated elsewhere) and closes the connection.
 
 ```js
 let openRequest = indexedDB.open("store", 2);
@@ -164,14 +162,16 @@ openRequest.onblocked = function() {
 */!*
 ```
 
-Here we do two things:
+...In other words, here we do two things:
+
+1. The `db.onversionchange` listener informs us about a parallel update attempt, if the current database version becomes outdated.
+2. The `openRequest.onblocked` listener informs us about the opposite situation: there's a connection to an outdated version elsewhere, and it doesn't close, so the newer connection can't be made.
 
-1. Add `db.onversionchange` listener after a successful opening, to be informed about a parallel update attempt.
-2. Add `openRequest.onblocked` listener to handle the case when an old connection wasn't closed. This doesn't happen if we close it in `db.onversionchange`.
+We can handle things more gracefully in `db.onversionchange`, prompt the visitor to save the data before the connection is closed and so on. 
 
-There are other variants. For example, we can take the time to close things gracefully in `db.onversionchange`, and prompt the visitor to save the data before the connection is closed. The new updating connection will be blocked immediately after `db.onversionchange` has finished without closing, and we can ask the visitor in the new tab to close other tabs for the update.
+Or, an alternative approach would be to not close the database in `db.onversionchange`, but instead use the `onblocked` handler (in the new tab) to alert the visitor, tell him that the newer version can't be loaded until they close other tabs.
 
-These update collisions happen rarely, but we should at least have some handling for them, e.g. `onblocked` handler, so that our script doesn't surprise the user by dying silently.
+These update collisions happen rarely, but we should at least have some handling for them, at least `onblocked` handler, to prevent our script from dying silently.
 
 ## Object store
 
@@ -475,24 +475,29 @@ request.onerror = function(event) {
 };
 ```
 
-## Searching by keys
+## Searching
 
 There are two main types of search in an object store:
-1. By a key or a key range. That is: by `book.id` in our "books" storage.
-2. By another object field, e.g. `book.price`.
 
-First let's deal with the first type of search: by a key.
+1. By a key value or a key range. In our "books" storage that would be a value or range of values of `book.id`.
+2. By another object field, e.g. `book.price`. This required an additional data structure, named "index".
+
+### By key
 
-Searching methods support both exact keys and so-called "ranges" -- [IDBKeyRange](https://www.w3.org/TR/IndexedDB/#keyrange) objects that specify an acceptable "key range".
+First let's deal with the first type of search: by key.
 
-Ranges are created using following calls:
+Searching methods support both exact key values and so-called "ranges of values" -- [IDBKeyRange](https://www.w3.org/TR/IndexedDB/#keyrange) objects that specify an acceptable "key range".
+
+`IDBKeyRange` objects are created using following calls:
 
 - `IDBKeyRange.lowerBound(lower, [open])` means: `≥lower` (or `>lower` if `open` is true)
 - `IDBKeyRange.upperBound(upper, [open])` means: `≤upper` (or `<upper` if `open` is true)
 - `IDBKeyRange.bound(lower, upper, [lowerOpen], [upperOpen])` means: between `lower` and `upper`. If the open flags is true, the corresponding key is not included in the range.
 - `IDBKeyRange.only(key)` -- a range that consists of only one `key`, rarely used.
 
-Searching methods accept a `query` argument that can be either an exact key or a key range:
+We'll see practical examples of using them very soon.
+
+To perform the actual search, there are following methods. They accept a `query` argument that can be either an exact key or a key range:
 
 - `store.get(query)` -- search for the first value by a key or a range.
 - `store.getAll([query], [count])` -- search for all values, limit by `count` if given.
@@ -522,13 +527,12 @@ books.getAllKeys(IDBKeyRange.lowerBound('js', true))
 ```
 
 ```smart header="Object store is always sorted"
-Object store sorts values by key internally.
+An object store sorts values by key internally.
 
 So requests that return many values always return them in sorted by key order.
 ```
 
-
-## Searching by any field with an index
+### By a field using an index
 
 To search by other object fields, we need to create an additional data structure named "index".