fix

1-js/02-first-steps/01-hello-world/article.md

@@ -63,7 +63,7 @@ Comments before and after scripts.
     //--></script>
     ```
 
-    These comments were supposed to hide the code from an old browser that didn't know about a `<script>` tag. But all browsers born in the past 15+ years don't have any issues. It is only mentioned here, because it serves as a sign. If you see that somewhere -- that code is probably really old and not worth looking into.
+    These comments were supposed to hide the code from an old browser that didn't know about a `<script>` tag. But all browsers born in the past 15+ years don't have any issues. We mention it here, because such comments serve as a sign. If you see that somewhere -- that code is probably really old and not worth looking into.
 
 
 ## External scripts
@@ -105,7 +105,7 @@ That saves traffic and makes pages faster.
 ```
 
 ````warn header="If `src` is set, the script content is ignored."
-A single `<script>` tag may not have both, `src` attribute and the code inside.
+A single `<script>` tag may not have both `src` attribute and the code inside.
 
 This won't work:
 

1-js/02-first-steps/09-alert-prompt-confirm/article.md

@@ -2,9 +2,7 @@
 
 This part of the tutorial aims to cover JavaScript "as is", without environment-specific tweaks.
 
-But still we use a browser as the demo environment. So we should know at least few user-interface functions.
-
-In this chapter we'll get familiar with the browser-specific functions `alert`, `prompt` and `confirm`.
+But still we use a browser as the demo environment. So we should know at least few user-interface functions. In this chapter we'll get familiar with the browser functions `alert`, `prompt` and `confirm`.
 
 [cut]
 

1-js/07-object-oriented-programming/01-property-descriptors/article.md

@@ -145,9 +145,7 @@ user.name = "Alice"; // Error
 
 Now let's add a custom `toString` to `user`.
 
-Normally, a built-in `toString` for objects is non-enumerable, it does not show up in `for..in`. But if we add `toString` of our own, then by default it shows up in `for..in`.
-
-...But if we don't like it, then we can set `enumerable:false`. Then it won't appear in `for..in` loop, just like the built-in one:
+Normally, a built-in `toString` for objects is non-enumerable, it does not show up in `for..in`. But if we add `toString` of our own, then by default it shows up in `for..in`, like this:
 
 ```js run
 let user = {
@@ -159,6 +157,17 @@ let user = {
 
 // By default, both our properties are listed:
 for(let key in user) alert(key); // name, toString
+```
+
+If we don't like it, then we can set `enumerable:false`. Then it won't appear in `for..in` loop, just like the built-in one:
+
+```js run
+let user = {
+  name: "John",
+  toString() {
+    return this.name;
+  }
+};
 
 Object.defineProperty(user, "toString", {
 *!*
@@ -167,7 +176,7 @@ Object.defineProperty(user, "toString", {
 });
 
 *!*
-// Now toString disappears:
+// Now our toString disappears:
 */!*
 for(let key in user) alert(key); // name
 ```
@@ -178,11 +187,9 @@ Non-enumerable properties are also excluded from `Object.keys`:
 alert(Object.keys(user)); // name
 ```
 
-
-
 ## Non-configurable
 
-The non-configurable flag (`configurable:false`) is usually set for built-in objects and properties.
+The non-configurable flag (`configurable:false`) is sometimes preset for built-in objects and properties.
 
 A non-configurable property can not be deleted or altered with `defineProperty`.