Merge pull request #689 from elie222/patch-1

Spelling fix

Author: iliakan

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

@@ -220,7 +220,7 @@ alert(obj.__proto__); // [object Object], didn't work as intended
 
 As we see from the code, the assignment to a primitive `5` is ignored.
 
-That can become a source of bugs and even vulnerabilies if we intend to store arbitrary key-value pairs in an object, and allow a visitor to specify the keys.
+That can become a source of bugs and even vulnerabilities if we intend to store arbitrary key-value pairs in an object, and allow a visitor to specify the keys.
 
 In that case the visitor may choose "__proto__" as the key, and the assignment logic will be ruined (as shown above).