Merge https://github.com/javascript-tutorial/pt.javascript.info into master

Author: ermogenes

1-js/02-first-steps/08-operators/article.md

@@ -106,6 +106,11 @@ alert(2 + 2 + '1' ); // "41" and not "221"
 
 Here, operators work one after another. The first `+` sums two numbers, so it returns `4`, then the next `+` adds the string `1` to it, so it's like `4 + '1' = 41`.
 
+```js run
+alert('1' + 2 + 2); // "122" and not "14"
+```
+Here, the first operand is a string, the compiler treats the other two operands as strings too. The `2` gets concatenated to `'1'`, so it's like `'1' + 2 = "12"` and `"12" + 2 = "122"`.
+
 The binary `+` is the only operator that supports strings in such a way. Other arithmetic operators work only with numbers and always convert their operands to numbers.
 
 Here's the demo for subtraction and division:

1-js/02-first-steps/10-ifelse/article.md

@@ -68,7 +68,7 @@ if (cond) {
 
 ## The "else" clause
 
-The `if` statement may contain an optional "else" block. It executes when the condition is false.
+The `if` statement may contain an optional "else" block. It executes when the condition is falsy.
 
 For example:
 ```js run

1-js/03-code-quality/06-polyfills/article.md

@@ -78,7 +78,7 @@ Two interesting libraries of polyfills are:
 
 ## Summary
 
-In this chapter we'd like to motivate you to study modern and even "bleeding-edge" langauge features, even if they aren't yet well-supported by JavaScript engines.
+In this chapter we'd like to motivate you to study modern and even "bleeding-edge" language features, even if they aren't yet well-supported by JavaScript engines.
 
 Just don't forget to use transpiler (if using modern syntax or operators) and polyfills (to add functions that may be missing). And they'll ensure that the code works.
 

1-js/05-data-types/03-string/3-truncate/solution.md

@@ -1,6 +1,6 @@
 The maximal length must be `maxlength`, so we need to cut it a little shorter, to give space for the ellipsis.
 
-Note that there is actually a single unicode character for an ellipsis. That's not three dots.
+Note that there is actually a single Unicode character for an ellipsis. That's not three dots.
 
 ```js run demo
 function truncate(str, maxlength) {

1-js/05-data-types/03-string/article.md

@@ -50,7 +50,7 @@ let guestList = "Guests: // Error: Unexpected token ILLEGAL
 
 Single and double quotes come from ancient times of language creation when the need for multiline strings was not taken into account. Backticks appeared much later and thus are more versatile.
 
-Backticks also allow us to specify a "template function" before the first backtick. The syntax is: <code>func&#96;string&#96;</code>. The function `func` is called automatically, receives the string and embedded expressions and can process them. This is called "tagged templates". This feature makes it easier to implement custom templating, but is rarely used in practice. You can read more about it in the [manual](mdn:/JavaScript/Reference/Template_literals#Tagged_templates). 
+Backticks also allow us to specify a "template function" before the first backtick. The syntax is: <code>func&#96;string&#96;</code>. The function `func` is called automatically, receives the string and embedded expressions and can process them. This is called "tagged templates". This feature makes it easier to implement custom templating, but is rarely used in practice. You can read more about it in the [manual](mdn:/JavaScript/Reference/Template_literals#Tagged_templates).
 
 ## Special characters
 
@@ -86,16 +86,16 @@ Here's the full list:
 |`\\`|Backslash|
 |`\t`|Tab|
 |`\b`, `\f`, `\v`| Backspace, Form Feed, Vertical Tab -- kept for compatibility, not used nowadays. |
-|`\xXX`|Unicode character with the given hexadecimal unicode `XX`, e.g. `'\x7A'` is the same as `'z'`.|
-|`\uXXXX`|A unicode symbol with the hex code `XXXX` in UTF-16 encoding, for instance `\u00A9` -- is a unicode for the copyright symbol `©`. It must be exactly 4 hex digits. |
-|`\u{X…XXXXXX}` (1 to 6 hex characters)|A unicode symbol with the given UTF-32 encoding. Some rare characters are encoded with two unicode symbols, taking 4 bytes. This way we can insert long codes. |
+|`\xXX`|Unicode character with the given hexadecimal Unicode `XX`, e.g. `'\x7A'` is the same as `'z'`.|
+|`\uXXXX`|A Unicode symbol with the hex code `XXXX` in UTF-16 encoding, for instance `\u00A9` -- is a Unicode for the copyright symbol `©`. It must be exactly 4 hex digits. |
+|`\u{X…XXXXXX}` (1 to 6 hex characters)|A Unicode symbol with the given UTF-32 encoding. Some rare characters are encoded with two Unicode symbols, taking 4 bytes. This way we can insert long codes. |
 
-Examples with unicode:
+Examples with Unicode:
 
 ```js run
 alert( "\u00A9" ); // ©
-alert( "\u{20331}" ); // 佫, a rare Chinese hieroglyph (long unicode)
-alert( "\u{1F60D}" ); // 😍, a smiling face symbol (another long unicode)
+alert( "\u{20331}" ); // 佫, a rare Chinese hieroglyph (long Unicode)
+alert( "\u{1F60D}" ); // 😍, a smiling face symbol (another long Unicode)
 ```
 
 All special characters start with a backslash character `\`. It is also called an "escape character".
@@ -499,7 +499,7 @@ All strings are encoded using [UTF-16](https://en.wikipedia.org/wiki/UTF-16). Th
     alert( String.fromCodePoint(90) ); // Z
     ```
 
-    We can also add unicode characters by their codes using `\u` followed by the hex code:
+    We can also add Unicode characters by their codes using `\u` followed by the hex code:
 
     ```js run
     // 90 is 5a in hexadecimal system
@@ -608,7 +608,7 @@ In many languages there are symbols that are composed of the base character with
 
 For instance, the letter `a` can be the base character for: `àáâäãåā`. Most common "composite" character have their own code in the UTF-16 table. But not all of them, because there are too many possible combinations.
 
-To support arbitrary compositions, UTF-16 allows us to use several unicode characters: the base character followed by one or many "mark" characters that "decorate" it.
+To support arbitrary compositions, UTF-16 allows us to use several Unicode characters: the base character followed by one or many "mark" characters that "decorate" it.
 
 For instance, if we have `S` followed by the special "dot above" character (code `\u0307`), it is shown as Ṡ.
 
@@ -626,7 +626,7 @@ For example:
 alert( 'S\u0307\u0323' ); // Ṩ
 ```
 
-This provides great flexibility, but also an interesting problem: two characters may visually look the same, but be represented with different unicode compositions.
+This provides great flexibility, but also an interesting problem: two characters may visually look the same, but be represented with different Unicode compositions.
 
 For instance:
 
@@ -639,7 +639,7 @@ alert( `s1: ${s1}, s2: ${s2}` );
 alert( s1 == s2 ); // false though the characters look identical (?!)
 ```
 
-To solve this, there exists a "unicode normalization" algorithm that brings each string to the single "normal" form.
+To solve this, there exists a "Unicode normalization" algorithm that brings each string to the single "normal" form.
 
 It is implemented by [str.normalize()](mdn:js/String/normalize).
 
@@ -663,7 +663,7 @@ If you want to learn more about normalization rules and variants -- they are des
 
 - There are 3 types of quotes. Backticks allow a string to span multiple lines and embed expressions `${…}`.
 - Strings in JavaScript are encoded using UTF-16.
-- We can use special characters like `\n` and insert letters by their unicode using `\u...`.
+- We can use special characters like `\n` and insert letters by their Unicode using `\u...`.
 - To get a character, use: `[]`.
 - To get a substring, use: `slice` or `substring`.
 - To lowercase/uppercase a string, use: `toLowerCase/toUpperCase`.

1-js/11-async/05-promise-api/article.md

@@ -309,15 +309,15 @@ In practice, this method is almost never used.
 
 ## Summary
 
-There are 5 static methods of `Promise` class:
+There are 6 static methods of `Promise` class:
 
 1. `Promise.all(promises)` -- waits for all promises to resolve and returns an array of their results. If any of the given promises rejects, it becomes the error of `Promise.all`, and all other results are ignored.
 2. `Promise.allSettled(promises)` (recently added method) -- waits for all promises to settle and returns their results as an array of objects with:
     - `status`: `"fulfilled"` or `"rejected"`
     - `value` (if fulfilled) or `reason` (if rejected).
 3. `Promise.race(promises)` -- waits for the first promise to settle, and its result/error becomes the outcome.
-4. `Promise.any(promises)` -- waits for the first promise to fulfill, and its result becomes the outcome. If all of the given promises are rejected, [`AggregateError`](mdn:js/AggregateError) becomes the error of `Promise.any`.
+4. `Promise.any(promises)` (recently added method) -- waits for the first promise to fulfill, and its result becomes the outcome. If all of the given promises are rejected, [`AggregateError`](mdn:js/AggregateError) becomes the error of `Promise.any`.
 5. `Promise.resolve(value)` -- makes a resolved promise with the given value.
 6. `Promise.reject(error)` -- makes a rejected promise with the given error.
 
-Of these five, `Promise.all` is probably the most common in practice.
+Of all these, `Promise.all` is probably the most common in practice.

1-js/99-js-misc/01-proxy/article.md

@@ -67,7 +67,7 @@ For every internal method, there's a trap in this table: the name of the method
 | `[[PreventExtensions]]` | `preventExtensions` | [Object.preventExtensions](mdn:/JavaScript/Reference/Global_Objects/Object/preventExtensions) |
 | `[[DefineOwnProperty]]` | `defineProperty` | [Object.defineProperty](mdn:/JavaScript/Reference/Global_Objects/Object/defineProperty), [Object.defineProperties](mdn:/JavaScript/Reference/Global_Objects/Object/defineProperties) |
 | `[[GetOwnProperty]]` | `getOwnPropertyDescriptor` | [Object.getOwnPropertyDescriptor](mdn:/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptor), `for..in`, `Object.keys/values/entries` |
-| `[[OwnPropertyKeys]]` | `ownKeys` | [Object.getOwnPropertyNames](mdn:/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames), [Object.getOwnPropertySymbols](mdn:/JavaScript/Reference/Global_Objects/Object/getOwnPropertySymbols), `for..in`, `Object/keys/values/entries` |
+| `[[OwnPropertyKeys]]` | `ownKeys` | [Object.getOwnPropertyNames](mdn:/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames), [Object.getOwnPropertySymbols](mdn:/JavaScript/Reference/Global_Objects/Object/getOwnPropertySymbols), `for..in`, `Object.keys/values/entries` |
 
 ```warn header="Invariants"
 JavaScript enforces some invariants -- conditions that must be fulfilled by internal methods and traps.

2-ui/2-events/05-dispatch-events/article.md

@@ -8,7 +8,7 @@ We can generate not only completely new events, that we invent for our own purpo
 
 ## Event constructor
 
-Build-in event classes form a hierarchy, similar to DOM element classes. The root is the built-in [Event](http://www.w3.org/TR/dom/#event) class.
+Built-in event classes form a hierarchy, similar to DOM element classes. The root is the built-in [Event](http://www.w3.org/TR/dom/#event) class.
 
 We can create `Event` objects like this:
 

2-ui/99-ui-misc/02-selection-range/article.md

@@ -155,7 +155,7 @@ We need to create a range, that:
   range.setStart(p.firstChild, 2);
   range.setEnd(p.querySelector('b').firstChild, 3);
 
-  alert(range); // ample: italic and bol
+  console.log(range); // ample: italic and bol
 
   // use this range for selection (explained later)
   window.getSelection().addRange(range);
@@ -211,7 +211,7 @@ With these methods we can do basically anything with selected nodes.
 
 Here's the test stand to see them in action:
 
-```html run autorun height=260
+```html run refresh autorun height=260
 Click buttons to run methods on the selection, "resetExample" to reset it.
 
 <p id="p">Example: <i>italic</i> and <b>bold</b></p>
@@ -244,7 +244,7 @@ Click buttons to run methods on the selection, "resetExample" to reset it.
       let newNode = document.createElement('u');
       try {
         range.surroundContents(newNode);
-      } catch(e) { alert(e) }
+      } catch(e) { console.log(e) }
     },
     resetExample() {
       p.innerHTML = `Example: <i>italic</i> and <b>bold</b>`;

4-binary/02-text-decoder/article.md

@@ -2,7 +2,7 @@
 
 What if the binary data is actually a string? For instance, we received a file with textual data.
 
-The build-in [TextDecoder](https://encoding.spec.whatwg.org/#interface-textdecoder) object allows to read the value into an an actual JavaScript string, given the buffer and the encoding.
+The build-in [TextDecoder](https://encoding.spec.whatwg.org/#interface-textdecoder) object allows to read the value into an actual JavaScript string, given the buffer and the encoding.
 
 We first need to create it:
 ```js
@@ -12,7 +12,7 @@ let decoder = new TextDecoder([label], [options]);
 - **`label`** -- the encoding, `utf-8` by default, but `big5`, `windows-1251` and many other are also supported.
 - **`options`** -- optional object:
   - **`fatal`** -- boolean, if `true` then throw an exception for invalid (non-decodable) characters, otherwise (default) replace them with character `\uFFFD`.
-  - **`ignoreBOM`** -- boolean, if `true` then ignore BOM (an optional byte-order unicode mark), rarely needed.
+  - **`ignoreBOM`** -- boolean, if `true` then ignore BOM (an optional byte-order Unicode mark), rarely needed.
 
 ...And then decode: