closes #3019

Author: iliakan

1-js/02-first-steps/13-while-for/article.md

@@ -6,6 +6,19 @@ For example, outputting goods from a list one after another or just running the
 
 *Loops* are a way to repeat the same code multiple times.
 
+```smart header="The for..of and for..in loops"
+A small announcement for advanced readers.
+
+This article covers only basic loops: `while`, `do..while` and `for(..;..;..)`.
+
+If you came to this article searching for other types of loops, here are the pointers:
+
+- See [for..in](info:object#forin) to loop over object properties.
+- See [for..of](info:array#loops) and [iterables](info:iterable) for looping over arrays and iterable objects.
+
+Otherwise, please read on.
+```
+
 ## The "while" loop
 
 The `while` loop has the following syntax:

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

@@ -355,7 +355,7 @@ In the code above, the property `obj.test` technically exists. So the `in` opera
 Situations like this happen very rarely, because `undefined` should not be explicitly assigned. We mostly use `null` for "unknown" or "empty" values. So the `in` operator is an exotic guest in the code.
 
 
-## The "for..in" loop
+## The "for..in" loop [#forin]
 
 To walk over all keys of an object, there exists a special form of the loop: `for..in`. This is a completely different thing from the `for(;;)` construct that we studied before.