minor fixes

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

@@ -186,6 +186,8 @@ let clone = Object.assign({}, user);
 
 It copies all properties of `user` into the empty object and returns it.
 
+There are also other methods of cloning an object, e.g. using the [spread operator](info:rest-parameters-spread) `clone = {...user}`, covered later in the tutorial.
+
 ## Nested cloning
 
 Until now we assumed that all properties of `user` are primitive. But properties can be references to other objects. What to do with them?

1-js/04-object-basics/07-optional-chaining/article.md

@@ -166,9 +166,9 @@ userGuest.admin?.(); // nothing (no such method)
 */!*
 ```
 
-Here, in both lines we first use the dot (`user1.admin`) to get `admin` property, because the user object must exist, so it's safe read from it.
+Here, in both lines we first use the dot (`userAdmin.admin`) to get `admin` property, because we assume that the user object exists, so it's safe read from it.
 
-Then `?.()` checks the left part: if the admin function exists, then it runs (that's so for `user1`). Otherwise (for `user2`) the evaluation stops without errors.
+Then `?.()` checks the left part: if the admin function exists, then it runs (that's so for `userAdmin`). Otherwise (for `userGuest`) the evaluation stops without errors.
 
 The `?.[]` syntax also works, if we'd like to use brackets `[]` to access properties instead of dot `.`. Similar to previous cases, it allows to safely read a property from an object that may not exist.