Merge branch 'master' of github.com:javascript-tutorial/en.javascript.info into sync-8d04d0d2

Author: iliakan

1-js/02-first-steps/05-types/article.md

@@ -213,14 +213,7 @@ The `symbol` type is used to create unique identifiers for objects. We have to m
 
 The `typeof` operator returns the type of the argument. It's useful when we want to process values of different types differently or just want to do a quick check.
 
-It supports two forms of syntax:
-
-1. As an operator: `typeof x`.
-2. As a function: `typeof(x)`.
-
-In other words, it works with parentheses or without them. The result is the same.
-
-The call to `typeof x` returns a string with the type name:
+A call to `typeof x` returns a string with the type name:
 
 ```js
 typeof undefined // "undefined"
@@ -251,9 +244,19 @@ typeof alert // "function"  (3)
 The last three lines may need additional explanation:
 
 1. `Math` is a built-in object that provides mathematical operations. We will learn it in the chapter <info:number>. Here, it serves just as an example of an object.
-2. The result of `typeof null` is `"object"`. That's an officially recognized error in `typeof` behavior, coming from the early days of JavaScript and kept for compatibility. Definitely, `null` is not an object. It is a special value with a separate type of its own.
+2. The result of `typeof null` is `"object"`. That's an officially recognized error in `typeof`, coming from very early days of JavaScript and kept for compatibility. Definitely, `null` is not an object. It is a special value with a separate type of its own. The behavior of `typeof` is wrong here.
 3. The result of `typeof alert` is `"function"`, because `alert` is a function. We'll study functions in the next chapters where we'll also see that there's no special "function" type in JavaScript. Functions belong to the object type. But `typeof` treats them differently, returning `"function"`. That also comes from the early days of JavaScript. Technically, such behavior isn't correct, but can be convenient in practice.
 
+```smart header="The `typeof(x)` syntax"
+You may also come across another syntax: `typeof(x)`. It's the same as `typeof x`.
+
+To put it clear: `typeof` is an operator, not a function. The parentheses here aren't a part of `typeof`. It's the kind of parentheses used for mathematical grouping.
+
+Usually, such parentheses contain a mathematical expression, such as `(2 + 2)`, but here they contain only one argument `(x)`. Syntactically, they allow to avoid a space between the `typeof` operator and its argument, and some people like it.
+
+Some people prefer `typeof(x)`, although the `typeof x` syntax is much more common.
+```
+
 ## Summary
 
 There are 8 basic data types in JavaScript.
@@ -269,7 +272,7 @@ There are 8 basic data types in JavaScript.
 
 The `typeof` operator allows us to see which type is stored in a variable.
 
-- Two forms: `typeof x` or `typeof(x)`.
+- Usually used as `typeof x`, but `typeof(x)` is also possible.
 - Returns a string with the name of the type, like `"string"`.
 - For `null` returns `"object"` -- this is an error in the language, it's not actually an object.
 

1-js/04-object-basics/04-object-methods/8-chain-calls/solution.md

@@ -23,7 +23,7 @@ let ladder = {
   }
 };
 
-ladder.up().up().down().up().down().showStep(); // 1
+ladder.up().up().down().showStep().down().showStep(); // shows 1 then 0
 ```
 
 We also can write a single call per line. For long chains it's more readable:
@@ -33,7 +33,7 @@ ladder
   .up()
   .up()
   .down()
-  .up()
+  .showStep() // 1
   .down()
-  .showStep(); // 1
+  .showStep(); // 0
 ```

1-js/04-object-basics/04-object-methods/8-chain-calls/task.md

@@ -28,12 +28,14 @@ ladder.up();
 ladder.up();
 ladder.down();
 ladder.showStep(); // 1
+ladder.down();
+ladder.showStep(); // 0
 ```
 
 Modify the code of `up`, `down` and `showStep` to make the calls chainable, like this:
 
 ```js
-ladder.up().up().down().showStep(); // 1
+ladder.up().up().down().showStep().down().showStep(); // shows 1 then 0
 ```
 
 Such approach is widely used across JavaScript libraries.

2-ui/3-event-details/6-pointer-events/article.md

@@ -271,7 +271,7 @@ Pointer events allow handling mouse, touch and pen events simultaneously, with a
 
 Pointer events extend mouse events. We can replace `mouse` with `pointer` in event names and expect our code to continue working for mouse, with better support for other device types.
 
-For drag'n'drops and complex touch interactions that the browser may decide to hijack and handle on its own - remember to cancel the default action on events and set `touch-events: none` in CSS for elements that we engage.
+For drag'n'drops and complex touch interactions that the browser may decide to hijack and handle on its own - remember to cancel the default action on events and set `touch-action: none` in CSS for elements that we engage.
 
 Additional abilities of pointer events are: