fixes

1-js/04-object-basics/01-object/article.md

@@ -92,30 +92,6 @@ let user = {
 ```
 That is called a "trailing" or "hanging" comma. Makes it easier to add/remove/move around properties, because all lines become alike.
 
-````smart header="Object with const can be changed"
-Please note: an object declared as `const` *can* be modified.
-
-For instance:
-
-```js run
-const user = {
-  name: "John"
-};
-
-*!*
-user.name = "Pete"; // (*)
-*/!*
-
-alert(user.name); // Pete
-```
-
-It might seem that the line `(*)` would cause an error, but no. The `const` fixes the value of `user`, but not its contents.
-
-The `const` would give an error only if we try to set `user=...` as a whole.
-
-There's another way to make constant object properties, we'll cover it later in the chapter <info:property-descriptors>.
-````
-
 ## Square brackets
 
 For multiword properties, the dot access doesn't work:

1-js/04-object-basics/02-object-copy/article.md

@@ -73,7 +73,6 @@ admin.name = 'Pete'; // changed by the "admin" reference
 alert(*!*user.name*/!*); // 'Pete', changes are seen from the "user" reference
 ```
 
-
 It's just as if we had a cabinet with two keys and used one of them (`admin`) to get into it. Then, if we later use another key (`user`) we can see changes.
 
 ## Comparison by reference
@@ -230,6 +229,30 @@ To fix that, we should use the cloning loop that examines each value of `user[ke
 
 We can use recursion to implement it. Or, not to reinvent the wheel, take an existing implementation, for instance [_.cloneDeep(obj)](https://lodash.com/docs#cloneDeep) from the JavaScript library [lodash](https://lodash.com).
 
+```smart header="Const objects can be modified"
+An important "side effect" of storing objects as references is that an object declared as `const` *can* be modified.
+
+For instance:
+
+```js run
+const user = {
+  name: "John"
+};
+
+*!*
+user.name = "Pete"; // (*)
+*/!*
+
+alert(user.name); // Pete
+```
+
+It might seem that the line `(*)` would cause an error, but no. The value of `user` is constant, it must always reference the same object. But properties of that object are free to change.
+
+In other words, the `const user` gives an error only if we try to set `user=...` as a whole, and that's all.
+
+That said, if we really need to make constant object properties, it's also possible, but using totally different methods, we'll mention that in the chapter <info:property-descriptors>.
+```
+
 ## Summary
 
 Objects are assigned and copied by reference. In other words, a variable stores not the "object value", but a "reference" (address in memory) for the value. So copying such a variable or passing it as a function argument copies that reference, not the object.

2-ui/4-forms-controls/3-events-change-input/article.md

@@ -76,11 +76,13 @@ For instance, the code below prevents all such events and shows what we are tryi
 
 Please note, that it's possible to copy/paste not just text, but everything. For instance, we can copy a file in the OS file manager, and paste it.
 
-There's a list of methods [in the specification](https://www.w3.org/TR/clipboard-apis/#dfn-datatransfer) that can work with different data types including files, read/write to the clipboard.
+That's because `clipboardData` implements `DataTransfer` interface, commonly used for drag'n'drop and copy/pasting. It's bit beyound our scope now, but you can find its methods [in the specification](https://html.spec.whatwg.org/multipage/dnd.html#the-datatransfer-interface).
 
-But please note that clipboard is a "global" OS-level thing. Most browsers allow read/write access to the clipboard only in the scope of certain user actions for the safety, e.g. in `onclick` event handlers.
+```warn header="ClipboardAPI: user safety restrictions"
+The clipboard is a "global" OS-level thing. So most browsers allow read/write access to the clipboard only in the scope of certain user actions for the safety, e.g. in `onclick` event handlers.
 
 Also it's forbidden to generate "custom" clipboard events with `dispatchEvent` in all browsers except Firefox.
+```
 
 ## Summary