Sync with upstream @ 035c5267

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: iliakan

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

@@ -94,6 +94,7 @@ const bigInt = 1234567890123456789012345678901234567890n;
 
 Քանի որ `BigInt` թվերը հազվադեպ են օգտագործվում, դրանց այստեղ չենք անդրադառնա, այլ կդիտարկենք առանձին՝ <info:bigint> գլխում։ Կարդացե՛ք այն, եթե նման մեծ թվերի օգտագոծման կարիք կունենաք։
 
+<<<<<<< HEAD
 
 ```smart header="Համատեղելիության խնդիրներ"
 Այս պահին `BigInt`-ը համատեղելի է Firefox/Chrome/Edge/Safari զննիչների հետ, բայց ոչ IE-ի։
@@ -102,6 +103,9 @@ const bigInt = 1234567890123456789012345678901234567890n;
 Կարող եք ստուգել [*MDN* BigInt compatibility table](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt#Browser_compatibility) հոդվածը, հասկանալու համար, թե զննիչների որ տարբերակների հետ է այն համատեղելի։
 
 ## Տող (String)
+=======
+## String
+>>>>>>> 035c5267ba80fa7b55878f7213cbde449b4092d9
 
 JavaScript-ում տողը պետք է շրջապատված լինի չակերտներով։
 

1-js/02-first-steps/16-function-expressions/article.md

@@ -82,7 +82,7 @@ let sayHi = function() { // (1) ստեղծել
   alert( "Ողջույն" );
 };
 
-let func = sayHi;
+let func = sayHi;  //(2)
 // ...
 ```
 

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

@@ -71,10 +71,7 @@ if (!Math.trunc) { // if no such function
 
 JavaScript is a highly dynamic language. Scripts may add/modify any function, even built-in ones.
 
-Two interesting polyfill libraries are:
-- [core js](https://github.com/zloirock/core-js) that supports a lot, allows to include only needed features.
-- [polyfill.io](https://polyfill.io/) service that provides a script with polyfills, depending on the features and user's browser.
-
+One interesting polyfill library is [core-js](https://github.com/zloirock/core-js), which supports a wide range of features and allows you to include only the ones you need.
 
 ## Summary
 

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

@@ -4,7 +4,7 @@ importance: 2
 
 # Chaining
 
-There's a `ladder` object that allows to go up and down:
+There's a `ladder` object that allows you to go up and down:
 
 ```js
 let ladder = {
@@ -21,7 +21,7 @@ let ladder = {
 };
 ```
 
-Now, if we need to make several calls in sequence, can do it like this:
+Now, if we need to make several calls in sequence, we can do it like this:
 
 ```js
 ladder.up();
@@ -32,10 +32,10 @@ ladder.down();
 ladder.showStep(); // 0
 ```
 
-Modify the code of `up`, `down` and `showStep` to make the calls chainable, like this:
+Modify the code of `up`, `down`, and `showStep` to make the calls chainable, like this:
 
 ```js
 ladder.up().up().down().showStep().down().showStep(); // shows 1 then 0
 ```
 
-Such approach is widely used across JavaScript libraries.
+Such an approach is widely used across JavaScript libraries.

1-js/04-object-basics/09-object-toprimitive/article.md

@@ -253,7 +253,7 @@ let obj = {
   }
 };
 
-alert(obj + 2); // 22 ("2" + 2), conversion to primitive returned a string => concatenation
+alert(obj + 2); // "22" ("2" + 2), conversion to primitive returned a string => concatenation
 ```
 
 ## Summary

1-js/05-data-types/02-number/article.md

@@ -4,7 +4,7 @@ In modern JavaScript, there are two types of numbers:
 
 1. Regular numbers in JavaScript are stored in 64-bit format [IEEE-754](https://en.wikipedia.org/wiki/IEEE_754), also known as "double precision floating point numbers". These are numbers that we're using most of the time, and we'll talk about them in this chapter.
 
-2. BigInt numbers represent integers of arbitrary length. They are sometimes needed because a regular integer number can't safely exceed <code>(2<sup>53</sup>-1)</code> or be less than <code>-(2<sup>53</sup>-1)</code>, as we mentioned earlier in the chapter <info:types>. As bigints are used in few special areas, we devote them a special chapter <info:bigint>.
+2. BigInt numbers represent integers of arbitrary length. They are sometimes needed because a regular integer number can't safely exceed <code>(2<sup>53</sup>-1)</code> or be less than <code>-(2<sup>53</sup>-1)</code>, as we mentioned earlier in the chapter <info:types>. As bigints are used in a few special areas, we devote them to a special chapter <info:bigint>.
 
 So here we'll talk about regular numbers. Let's expand our knowledge of them.
 
@@ -41,7 +41,7 @@ In other words, `e` multiplies the number by `1` with the given zeroes count.
 1.23e6 === 1.23 * 1000000; // e6 means *1000000
 ```
 
-Now let's write something very small. Say, 1 microsecond (one millionth of a second):
+Now let's write something very small. Say, 1 microsecond (one-millionth of a second):
 
 ```js
 let mсs = 0.000001;
@@ -103,13 +103,13 @@ alert( num.toString(16) );  // ff
 alert( num.toString(2) );   // 11111111
 ```
 
-The `base` can vary from `2` to `36`. By default it's `10`.
+The `base` can vary from `2` to `36`. By default, it's `10`.
 
 Common use cases for this are:
 
 - **base=16** is used for hex colors, character encodings etc, digits can be `0..9` or `A..F`.
 - **base=2** is mostly for debugging bitwise operations, digits can be `0` or `1`.
-- **base=36** is the maximum, digits can be `0..9` or `A..Z`. The whole latin alphabet is used to represent a number. A funny, but useful case for `36` is when we need to turn a long numeric identifier into something shorter, for example to make a short url. Can simply represent it in the numeral system with base `36`:
+- **base=36** is the maximum, digits can be `0..9` or `A..Z`. The whole Latin alphabet is used to represent a number. A funny, but useful case for `36` is when we need to turn a long numeric identifier into something shorter, for example, to make a short url. Can simply represent it in the numeral system with base `36`:
 
     ```js run
     alert( 123456..toString(36) ); // 2n9c
@@ -118,7 +118,7 @@ Common use cases for this are:
 ```warn header="Two dots to call a method"
 Please note that two dots in `123456..toString(36)` is not a typo. If we want to call a method directly on a number, like `toString` in the example above, then we need to place two dots `..` after it.
 
-If we placed a single dot: `123456.toString(36)`, then there would be an error, because JavaScript syntax implies the decimal part after the first dot. And if we place one more dot, then JavaScript knows that the decimal part is empty and now goes the method.
+If we placed a single dot: `123456.toString(36)`, then there would be an error, because JavaScript syntax implies the decimal part after the first dot. And if we place one more dot, then JavaScript knows that the decimal part is empty and now uses the method.
 
 Also could write `(123456).toString(36)`.
 
@@ -137,7 +137,7 @@ There are several built-in functions for rounding:
 : Rounds up: `3.1` becomes `4`, and `-1.1` becomes `-1`.
 
 `Math.round`
-: Rounds to the nearest integer: `3.1` becomes `3`, `3.6` becomes `4`, the middle case: `3.5` rounds up to `4` too.
+: Rounds to the nearest integer: `3.1` becomes `3`, `3.6` becomes `4`. In the middle cases `3.5` rounds up to `4`, and `-3.5` rounds up to `-3`.
 
 `Math.trunc` (not supported by Internet Explorer)
 : Removes anything after the decimal point without rounding: `3.1` becomes `3`, `-1.1` becomes `-1`.
@@ -147,8 +147,10 @@ Here's the table to summarize the differences between them:
 |   | `Math.floor` | `Math.ceil` | `Math.round` | `Math.trunc` |
 |---|---------|--------|---------|---------|
 |`3.1`|  `3`    |   `4`  |    `3`  |   `3`   |
+|`3.5`|  `3`    |   `4`  |    `4`  |   `3`   |
 |`3.6`|  `3`    |   `4`  |    `4`  |   `3`   |
 |`-1.1`|  `-2`    |   `-1`  |    `-1`  |   `-1`   |
+|`-1.5`|  `-2`    |   `-1`  |    `-1`  |   `-1`   |
 |`-1.6`|  `-2`    |   `-1`  |    `-2`  |   `-1`   |
 
 
@@ -188,7 +190,7 @@ There are two ways to do so:
     alert( num.toFixed(5) ); // "12.34000", added zeroes to make exactly 5 digits
     ```
 
-    We can convert it to a number using the unary plus or a `Number()` call, e.g write `+num.toFixed(5)`.
+    We can convert it to a number using the unary plus or a `Number()` call, e.g. write `+num.toFixed(5)`.
 
 ## Imprecise calculations
 
@@ -222,7 +224,13 @@ But why does this happen?
 
 A number is stored in memory in its binary form, a sequence of bits - ones and zeroes. But fractions like `0.1`, `0.2` that look simple in the decimal numeric system are actually unending fractions in their binary form.
 
-What is `0.1`? It is one divided by ten `1/10`, one-tenth. In decimal numeral system such numbers are easily representable. Compare it to one-third: `1/3`. It becomes an endless fraction `0.33333(3)`.
+```js run
+alert(0.1.toString(2)); // 0.0001100110011001100110011001100110011001100110011001101
+alert(0.2.toString(2)); // 0.001100110011001100110011001100110011001100110011001101
+alert((0.1 + 0.2).toString(2)); // 0.0100110011001100110011001100110011001100110011001101
+```
+
+What is `0.1`? It is one divided by ten `1/10`, one-tenth. In the decimal numeral system, such numbers are easily representable. Compare it to one-third: `1/3`. It becomes an endless fraction `0.33333(3)`.
 
 So, division by powers `10` is guaranteed to work well in the decimal system, but division by `3` is not. For the same reason, in the binary numeral system, the division by powers of `2` is guaranteed to work, but `1/10` becomes an endless binary fraction.
 
@@ -242,7 +250,7 @@ That's why `0.1 + 0.2` is not exactly `0.3`.
 ```smart header="Not only JavaScript"
 The same issue exists in many other programming languages.
 
-PHP, Java, C, Perl, Ruby give exactly the same result, because they are based on the same numeric format.
+PHP, Java, C, Perl, and Ruby give exactly the same result, because they are based on the same numeric format.
 ```
 
 Can we work around the problem? Sure, the most reliable method is to round the result with the help of a method [toFixed(n)](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed):
@@ -266,7 +274,7 @@ alert( (0.1 * 10 + 0.2 * 10) / 10 ); // 0.3
 alert( (0.28 * 100 + 0.14 * 100) / 100); // 0.4200000000000001
 ```
 
-So, multiply/divide approach reduces the error, but doesn't remove it totally.
+So, the multiply/divide approach reduces the error, but doesn't remove it totally.
 
 Sometimes we could try to evade fractions at all. Like if we're dealing with a shop, then we can store prices in cents instead of dollars. But what if we apply a discount of 30%? In practice, totally evading fractions is rarely possible. Just round them to cut "tails" when needed.
 
@@ -288,7 +296,7 @@ Another funny consequence of the internal representation of numbers is the exist
 
 That's because a sign is represented by a single bit, so it can be set or not set for any number including a zero.
 
-In most cases the distinction is unnoticeable, because operators are suited to treat them as the same.
+In most cases, the distinction is unnoticeable, because operators are suited to treat them as the same.
 ```
 
 ## Tests: isFinite and isNaN
@@ -337,7 +345,7 @@ Please note that an empty or a space-only string is treated as `0` in all numeri
 ````smart header="`Number.isNaN` and `Number.isFinite`"
 [Number.isNaN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN) and [Number.isFinite](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isFinite) methods are the more "strict" versions of `isNaN` and `isFinite` functions. They do not autoconvert their argument into a number, but check if it belongs to the `number` type instead.
 
-- `Number.isNaN(value)` returns `true` if the argument belongs to the `number` type and it is `NaN`. In any other case it returns `false`.
+- `Number.isNaN(value)` returns `true` if the argument belongs to the `number` type and it is `NaN`. In any other case, it returns `false`.
 
     ```js run
     alert( Number.isNaN(NaN) ); // true
@@ -348,7 +356,7 @@ Please note that an empty or a space-only string is treated as `0` in all numeri
     alert( isNaN("str") ); // true, because isNaN converts string "str" into a number and gets NaN as a result of this conversion
     ```
 
-- `Number.isFinite(value)` returns `true` if the argument belongs to the `number` type and it is not `NaN/Infinity/-Infinity`. In any other case it returns `false`.
+- `Number.isFinite(value)` returns `true` if the argument belongs to the `number` type and it is not `NaN/Infinity/-Infinity`. In any other case, it returns `false`.
 
     ```js run
     alert( Number.isFinite(123) ); // true
@@ -367,7 +375,7 @@ In a way, `Number.isNaN` and `Number.isFinite` are simpler and more straightforw
 There is a special built-in method `Object.is` that compares values like `===`, but is more reliable for two edge cases:
 
 1. It works with `NaN`: `Object.is(NaN, NaN) === true`, that's a good thing.
-2. Values `0` and `-0` are different: `Object.is(0, -0) === false`, technically that's correct, because internally the number has a sign bit that may be different even if all other bits are zeroes.
+2. Values `0` and `-0` are different: `Object.is(0, -0) === false`, technically that's correct because internally the number has a sign bit that may be different even if all other bits are zeroes.
 
 In all other cases, `Object.is(a, b)` is the same as `a === b`.
 
@@ -385,7 +393,7 @@ alert( +"100px" ); // NaN
 
 The sole exception is spaces at the beginning or at the end of the string, as they are ignored.
 
-But in real life we often have values in units, like `"100px"` or `"12pt"` in CSS. Also in many countries the currency symbol goes after the amount, so we have `"19€"` and would like to extract a numeric value out of that.
+But in real life, we often have values in units, like `"100px"` or `"12pt"` in CSS. Also in many countries, the currency symbol goes after the amount, so we have `"19€"` and would like to extract a numeric value out of that.
 
 That's what `parseInt` and `parseFloat` are for.
 
@@ -479,4 +487,4 @@ For fractions:
 
 More mathematical functions:
 
-- See the [Math](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Math) object when you need them. The library is very small, but can cover basic needs.
+- See the [Math](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Math) object when you need them. The library is very small but can cover basic needs.

1-js/05-data-types/04-array/article.md

@@ -426,7 +426,7 @@ let matrix = [
   [7, 8, 9]
 ];
 
-alert( matrix[1][1] ); // 5, the central element
+alert( matrix[0][1] ); // 2, the second value of the first inner array
 ```
 
 ## toString