merging all conflicts

Author: root

1-js/01-getting-started/1-intro/article.md

@@ -105,13 +105,25 @@ Javascript – це єдина браузерна технологія, яка 
 
 Сучасні інструменти роблять транспіляцію дуже швидкою і прозорою, дозволяючи розробникам писати код іншою мовою і автоматично конвертувати його "під капотом".
 
+<<<<<<< HEAD
 Приклади таких мов:
 
 - [CoffeeScript](http://coffeescript.org/) це "синтаксичний цукор" поверх JavaScript. Вона вводить більш короткий синтаксис, дозволяючи нам писати більш чіткий і точний код. Зазвичай, програмісти на Ruby люблять її.
 - [TypeScript](http://www.typescriptlang.org/) зосереджена на додаванні "строгої типізації даних", щоб спростити розробку і підтримку складних систем. ЇЇ розробляє Microsoft.
 - [Dart](https://www.dartlang.org/) це автономна мова, яка має власний рушій, який виконується в не-браузерних середовищах (таких як, мобільні застосунки). Спочатку компанія Google запропонувала її як заміну JavaScript, але на даний момент, браузери використовують її для транспіляції в JavaScript так само, як інструменти вище.
 
 Їх є ще більше. Звичайно, навіть якщо ми використовуємо одну з цих мов, ми також повинні знати JavaScript, щоб дійсно розуміти, що робимо.
+=======
+The most used are
+Examples of such languages:
+
+- [CoffeeScript](http://coffeescript.org/) is a "syntactic sugar" for JavaScript. It introduces shorter syntax, allowing us to write clearer and more precise code. Usually, Ruby devs like it.
+- [TypeScript](http://www.typescriptlang.org/) is concentrated on adding "strict data typing" to simplify the development and support of complex systems. It is developed by Microsoft.
+- [Flow](http://flow.org/) also adds data typing, but in a different way. Developed by Facebook.
+- [Dart](https://www.dartlang.org/) is a standalone language that has its own engine that runs in non-browser environments (like mobile apps), but also can be transpiled to JavaScript. Developed by Google.
+
+There are more. Of course, even if we use one of transpiled languages, we should also know JavaScript to really understand what we're doing.
+>>>>>>> 9b5c1c95ec8a466150e519b0e94748717c747b09
 
 ## Підсумки
 

1-js/01-getting-started/2-manuals-specifications/article.md

@@ -0,0 +1,43 @@
+
+# Manuals and specifications
+
+This book is a *tutorial*. It aims to help you gradually learn the language. But once you're familiar with the basics, you'll need other sources.
+
+
+## Specification
+
+**The ECMA-262 specification** contains the most in-depth, detailed and formalized information about JavaScript. It defines the language.
+
+But being that formalized, it's difficult to understand at first. So if you need the most trustworthy source of information about the language details, it's the right place. But it's not for everyday use.
+
+The latest draft is at <https://tc39.es/ecma262/>.
+
+To read about bleeding-edge features, that are not yet widely supported, see proposals at <https://github.com/tc39/proposals>.
+
+Also, if you're in developing for the browser, then there are other specs covered in the [second part](info:browser-environment) of the tutorial.
+
+## Manuals
+
+- **MDN (Mozilla) JavaScript Reference** is a manual with examples and other information. It's great to get in-depth information about individual language functions, methods etc.
+
+    One can find it at <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference>.
+
+    Although, it's often best to use an internet search instead. Just use "MDN [term]" in the query, e.g. <https://google.com/search?q=MDN+parseInt> to search for `parseInt` function.
+
+
+- **MSDN** – Microsoft manual with a lot of information, including JavaScript (often referrerd to as JScript). If one needs something specific to Internet Explorer, better go there: <http://msdn.microsoft.com/>.
+
+    Also, we can use an internet search with phrases such as "RegExp MSDN" or "RegExp MSDN jscript".
+
+## Feature support
+
+JavaScript is a developing language, new features get added regularly.
+
+To see their support among browser-based and other engines, see:
+
+- <http://caniuse.com> - per-feature tables of support, e.g. to see which engines support modern cryptography functions: <http://caniuse.com/#feat=cryptography>.
+- <https://kangax.github.io/compat-table> - a table with language features and engines that support those or don't support.
+
+All these resources are useful in real-life development, as they contain valuable information about language details, their support etc.
+
+Please remember them (or this page) for the cases when you need in-depth information about a particular feature.

1-js/01-getting-started/2-code-editors/article.md renamed to 1-js/01-getting-started/3-code-editors/article.md

@@ -304,8 +304,8 @@ Here's an example of an `.eslintrc` file:
   },
   "rules": {
     "no-console": 0,
-  },
-  "indent": 2
+    "indent": ["warning", 2]
+  }
 }
 ```
 

1-js/01-getting-started/3-devtools/article.md renamed to 1-js/01-getting-started/4-devtools/article.md

@@ -74,7 +74,9 @@ alert(id.description); // id
 
 Symbols allow us to create "hidden" properties of an object, that no other part of code can occasionally access or overwrite.
 
-For instance, if we'd like to add an "identifier" to the object `user`, we can use a symbol as a key for it:
+For instance, if we're working with `user` objects, that belong to a third-party code and don't have any `id` field. We'd like to add identifiers to them.
+
+Let's use a symbol key for it:
 
 ```js run
 let user = { name: "John" };
@@ -86,9 +88,9 @@ alert( user[id] ); // we can access the data using the symbol as the key
 
 What's the benefit of using `Symbol("id")` over a string `"id"`?
 
-Let's make the example a bit deeper to see that.
+As `user` objects belongs to another code, and that code also works with them, we shouldn't just add any fields to it. That's unsafe. But a symbol cannot be accessed occasionally, the third-party code probably won't even see it, so it's probably all right to do.
 
-Imagine that another script wants to have its own identifier inside `user`, for its own purposes. That may be another JavaScript library, so thes scripts are completely unaware of each other.
+Also, imagine that another script wants to have its own identifier inside `user`, for its own purposes. That may be another JavaScript library, so that the scripts are completely unaware of each other.
 
 Then that script can create its own `Symbol("id")`, like this:
 

1-js/01-getting-started/3-devtools/bug.html renamed to 1-js/01-getting-started/4-devtools/bug.html

@@ -15,13 +15,13 @@ The error message in most browsers does not give understanding what went wrong.
 
 **The error appears because a semicolon is missing after `user = {...}`.**
 
-JavaScript does not assume a semicolon before a bracket `(user.go)()`, so it reads the code like:
+JavaScript does not auto-insert a semicolon before a bracket `(user.go)()`, so it reads the code like:
 
 ```js no-beautify
 let user = { go:... }(user.go)()
 ```
 
-Then we can also see that such a joint expression is syntactically a call of the object `{ go: ... }` as a function with the argument `(user.go)`. And that also happens on the same line with `let user`, so the `user` object has not yet even been defined, hence the error. 
+Then we can also see that such a joint expression is syntactically a call of the object `{ go: ... }` as a function with the argument `(user.go)`. And that also happens on the same line with `let user`, so the `user` object has not yet even been defined, hence the error.
 
 If we insert the semicolon, all is fine:
 
@@ -35,9 +35,3 @@ let user = {
 ```
 
 Please note that brackets around `(user.go)` do nothing here. Usually they setup the order of operations, but here the dot `.` works first anyway, so there's no effect. Only the semicolon thing matters.
-
-
-
-
-
-

1-js/01-getting-started/3-devtools/chrome.png renamed to 1-js/01-getting-started/4-devtools/chrome.png

@@ -14,11 +14,11 @@ let user = makeUser();
 alert( user.ref.name ); // Error: Cannot read property 'name' of undefined
 ```
 
-That's because rules that set `this` do not look at object literals. 
+That's because rules that set `this` do not look at object definition. Only the moment of call matters.
 
-Here the value of `this` inside `makeUser()` is `undefined`, because it is called as a function, not as a method.
+Here the value of `this` inside `makeUser()` is `undefined`, because it is called as a function, not as a method with "dot" syntax.
 
-And the object literal itself has no effect on `this`. The value of `this` is one for the whole function, code blocks and object literals do not affect it.
+The value of `this` is one for the whole function, code blocks and object literals do not affect it.
 
 So `ref: this` actually takes current `this` of the function.
 
@@ -42,5 +42,3 @@ alert( user.ref().name ); // John
 ```
 
 Now it works, because `user.ref()` is a method. And the value of `this` is set to the object before dot `.`.
-
-

1-js/01-getting-started/3-devtools/[email protected] renamed to 1-js/01-getting-started/4-devtools/[email protected]

@@ -15,7 +15,7 @@ Actions are represented in JavaScript by functions in properties.
 
 ## Method examples
 
-For the start, let's teach the `user` to say hello:
+For a start, let's teach the `user` to say hello:
 
 ```js run
 let user = {
@@ -257,11 +257,11 @@ user.hi(); // John (the simple call works)
 */!*
 ```
 
-On the last line there is a ternary operator that chooses either `user.hi` or `user.bye`. In this case the result is `user.hi`.
+On the last line there is a conditinal operator that chooses either `user.hi` or `user.bye`. In this case the result is `user.hi`.
 
-The method is immediately called with parentheses `()`. But it doesn't work right!
+Then the method is immediately called with parentheses `()`. But it doesn't work right!
 
-You can see that the call results in an error, because the value of `"this"` inside the call becomes `undefined`.
+As you can see, the call results in an error, because the value of `"this"` inside the call becomes `undefined`.
 
 This works (object dot method):
 ```js
@@ -306,7 +306,7 @@ The Reference Type is a "specification type". We can't explicitly use it, but it
 The value of Reference Type is a three-value combination `(base, name, strict)`, where:
 
 - `base` is the object.
-- `name` is the property.
+- `name` is the property name.
 - `strict` is true if `use strict` is in effect.
 
 The result of a property access `user.hi` is not a function, but a value of Reference Type. For `user.hi` in strict mode it is:
@@ -318,6 +318,8 @@ The result of a property access `user.hi` is not a function, but a value of Refe
 
 When parentheses `()` are called on the Reference Type, they receive the full information about the object and its method, and can set the right `this` (`=user` in this case).
 
+Reference type is a special "intermediary" internal type, with the purpose to pass information from dot `.` to calling parentheses `()`.
+
 Any other operation like assignment `hi = user.hi` discards the reference type as a whole, takes the value of `user.hi` (a function) and passes it on. So any further operation "loses" `this`.
 
 So, as the result, the value of `this` is only passed the right way if the function is called directly using a dot `obj.method()` or square brackets `obj['method']()` syntax (they do the same here). Later in this tutorial, we will learn various ways to solve this problem such as [func.bind()](/bind#solution-2-bind).

1-js/01-getting-started/3-devtools/safari.png renamed to 1-js/01-getting-started/4-devtools/safari.png

@@ -11,7 +11,7 @@ We already know methods that add and remove items from the beginning or the end:
 - `arr.shift()` -- extracts an item from the beginning,
 - `arr.unshift(...items)` -- adds items to the beginning.
 
-Here are few others.
+Here are a few others.
 
 ### splice
 
@@ -238,7 +238,7 @@ These are methods to search for something in an array.
 
 The methods [arr.indexOf](mdn:js/Array/indexOf), [arr.lastIndexOf](mdn:js/Array/lastIndexOf) and [arr.includes](mdn:js/Array/includes) have the same syntax and do essentially the same as their string counterparts, but operate on items instead of characters:
 
-- `arr.indexOf(item, from)` looks for `item` starting from index `from`, and returns the index where it was found, otherwise `-1`.
+- `arr.indexOf(item, from)` -- looks for `item` starting from index `from`, and returns the index where it was found, otherwise `-1`.
 - `arr.lastIndexOf(item, from)` -- same, but looks for from right to left.
 - `arr.includes(item, from)` -- looks for `item` starting from index `from`, returns `true` if found.
 
@@ -418,7 +418,7 @@ alert(arr);  // *!*1, 2, 15*/!*
 
 Now it works as intended.
 
-Let's step aside and think what's happening. The `arr` can be array of anything, right? It may contain numbers or strings or html elements or whatever. We have a set of *something*. To sort it, we need an *ordering function* that knows how to compare its elements. The default is a string order.
+Let's step aside and think what's happening. The `arr` can be array of anything, right? It may contain numbers or strings or HTML elements or whatever. We have a set of *something*. To sort it, we need an *ordering function* that knows how to compare its elements. The default is a string order.
 
 The `arr.sort(fn)` method has a built-in implementation of sorting algorithm. We don't need to care how it exactly works (an optimized [quicksort](https://en.wikipedia.org/wiki/Quicksort) most of the time). It will walk the array, compare its elements using the provided function and reorder them, all we need is to provide the `fn` which does the comparison.
 
@@ -474,7 +474,7 @@ It also returns the array `arr` after the reversal.
 
 ### split and join
 
-Here's the situation from the real life. We are writing a messaging app, and the person enters the comma-delimited list of receivers: `John, Pete, Mary`. But for us an array of names would be much more comfortable than a single string. How to get it?
+Here's the situation from real life. We are writing a messaging app, and the person enters the comma-delimited list of receivers: `John, Pete, Mary`. But for us an array of names would be much more comfortable than a single string. How to get it?
 
 The [str.split(delim)](mdn:js/String/split) method does exactly that. It splits the string into an array by the given delimiter `delim`.
 
@@ -548,7 +548,7 @@ So far, like `forEach/map`. But there's one more argument:
 
 The easiest way to grasp that is by example.
 
-Here we get a sum of array in one line:
+Here we get a sum of an array in one line:
 
 ```js run
 let arr = [1, 2, 3, 4, 5];
@@ -681,7 +681,7 @@ In the call above, we use `user.younger` as a filter and also provide `user` as
 
 ## Summary
 
-A cheatsheet of array methods:
+A cheat sheet of array methods:
 
 - To add/remove elements:
   - `push(...items)` -- adds items to the end,
@@ -727,6 +727,6 @@ For the full list, see the [manual](mdn:js/Array).
 
 From the first sight it may seem that there are so many methods, quite difficult to remember. But actually that's much easier than it seems.
 
-Look through the cheatsheet just to be aware of them. Then solve the tasks of this chapter to practice, so that you have experience with array methods.
+Look through the cheat sheet just to be aware of them. Then solve the tasks of this chapter to practice, so that you have experience with array methods.
 
-Afterwards whenever you need to do something with an array, and you don't know how -- come here, look at the cheatsheet and find the right method. Examples will help you to write it correctly. Soon you'll automatically remember the methods, without specific efforts from your side.
+Afterwards whenever you need to do something with an array, and you don't know how -- come here, look at the cheat sheet and find the right method. Examples will help you to write it correctly. Soon you'll automatically remember the methods, without specific efforts from your side.

1-js/01-getting-started/3-devtools/[email protected] renamed to 1-js/01-getting-started/4-devtools/[email protected]

@@ -17,9 +17,9 @@ Write the destructuring assignment that reads:
 
 - `name` property into the variable `name`.
 - `years` property into the variable `age`.
-- `isAdmin` property into the variable `isAdmin` (false if absent)
+- `isAdmin` property into the variable `isAdmin` (false, if no such property)
 
-The values after the assignment should be:
+Here's an example of the values after your assignment:
 
 ```js
 let user = { name: "John", years: 30 };