Sync with upstream @ 70ca842b

1-js/04-object-basics/04-object-methods/3-why-this/task.md

@@ -4,7 +4,7 @@ importance: 3
 
 # Explain the value of "this"
 
-In the code below we intend to call `user.go()` method 4 times in a row.
+In the code below we intend to call `obj.go()` method 4 times in a row.
 
 But calls `(1)` and `(2)` works differently from `(3)` and `(4)`. Why?
 

1-js/05-data-types/05-array-methods/4-sort-back/task.md

@@ -2,12 +2,12 @@ importance: 4
 
 ---
 
-# Sort in the reverse order
+# Sort in decreasing order
 
 ```js
 let arr = [5, 2, 1, -10, 8];
 
-// ... your code to sort it in the reverse order
+// ... your code to sort it in decreasing order
 
 alert( arr ); // 8, 5, 2, 1, -10
 ```

1-js/06-advanced-functions/08-settimeout-setinterval/article.md

@@ -288,7 +288,7 @@ For server-side JavaScript, that limitation does not exist, and there exist othe
 
 - Methods `setTimeout(func, delay, ...args)` and `setInterval(func, delay, ...args)` allow us to run the `func` once/regularly after `delay` milliseconds.
 - To cancel the execution, we should call `clearTimeout/clearInterval` with the value returned by `setTimeout/setInterval`.
-- Nested `setTimeout` calls is a more flexible alternative to `setInterval`, allowing us to set the time *between* executions more precisely.
+- Nested `setTimeout` calls are a more flexible alternative to `setInterval`, allowing us to set the time *between* executions more precisely.
 - Zero delay scheduling with `setTimeout(func, 0)` (the same as `setTimeout(func)`) is used to schedule the call "as soon as possible, but after the current script is complete".
 - The browser limits the minimal delay for five or more nested call of `setTimeout` or for `setInterval` (after 5th call) to 4ms. That's for historical reasons.
 

1-js/06-advanced-functions/10-bind/6-ask-partial/task.md

@@ -8,7 +8,7 @@ The task is a little more complex variant of <info:task/question-use-bind>.
 
 The `user` object was modified. Now instead of two functions `loginOk/loginFail`, it has a single function `user.login(true/false)`.
 
-What to pass `askPassword` in the code below, so that it calls `user.login(true)` as `ok` and `user.login(false)` as `fail`?
+What should we pass `askPassword` in the code below, so that it calls `user.login(true)` as `ok` and `user.login(false)` as `fail`?
 
 ```js
 function askPassword(ok, fail) {

1-js/06-advanced-functions/10-bind/article.md

@@ -98,7 +98,7 @@ Functions provide a built-in method [bind](mdn:js/Function/bind) that allows to
 The basic syntax is:
 
 ```js
-// more complex syntax will be little later
+// more complex syntax will come a little later
 let boundFunc = func.bind(context);
 ```
 

1-js/06-advanced-functions/12-arrow-functions/article.md

@@ -118,9 +118,9 @@ Here we had to create additional variables `args` and `ctx` so that the function
 
 Arrow functions:
 
-- Do not have `this`.
-- Do not have `arguments`.
-- Can't be called with `new`.
-- (They also don't have `super`, but we didn't study it. Will be in the chapter <info:class-inheritance>).
+- Do not have `this`
+- Do not have `arguments`
+- Can't be called with `new`
+- They also don't have `super`, but we didn't study it yet. We will on the chapter <info:class-inheritance>
 
-That's because they are meant for short pieces of code that do not have their own "context", but rather works in the current one. And they really shine in that use case.
+That's because they are meant for short pieces of code that do not have their own "context", but rather work in the current one. And they really shine in that use case.

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

@@ -3,7 +3,7 @@
 
 As we know, objects can store properties.
 
-Till now, a property was a simple "key-value" pair to us. But an object property is actually a more flexible and powerful thing.
+Until now, a property was a simple "key-value" pair to us. But an object property is actually a more flexible and powerful thing.
 
 In this chapter we'll study additional configuration options, and in the next we'll see how to invisibly turn them into getter/setter functions.
 
@@ -134,7 +134,7 @@ let user = { };
 Object.defineProperty(user, "name", {
 *!*
   value: "John",
-  // for new properties need to explicitly list what's true
+  // for new properties we need to explicitly list what's true
   enumerable: true,
   configurable: true
 */!*
@@ -148,7 +148,7 @@ user.name = "Pete"; // 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`, like this:
+Normally, a built-in `toString` for objects is non-enumerable, it does not show up in `for..in`. But if we add a `toString` of our own, then by default it shows up in `for..in`, like this:
 
 ```js run
 let user = {
@@ -162,7 +162,7 @@ let user = {
 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:
+If we don't like it, then we can set `enumerable:false`. Then it won't appear in a `for..in` loop, just like the built-in one:
 
 ```js run
 let user = {

1-js/07-object-properties/02-property-accessors/article.md

@@ -3,7 +3,7 @@
 
 There are two kinds of properties.
 
-The first kind is *data properties*. We already know how to work with them. All properties that we've been using till now were data properties.
+The first kind is *data properties*. We already know how to work with them. All properties that we've been using until now were data properties.
 
 The second type of properties is something new. It's *accessor properties*. They are essentially functions that work on getting and setting a value, but look like regular properties to an external code.
 
@@ -189,9 +189,9 @@ Technically, external code is able to access the name directly by using `user._n
 
 ## Using for compatibility
 
-One of the great uses of accessors -- they allow to take control over a "regular" data property at any moment by replacing it with getter and setter and tweak its behavior.
+One of the great uses of accessors is that they allow to take control over a "regular" data property at any moment by replacing it with a getter and a setter and tweak its behavior.
 
-Imagine, we started implementing user objects using data properties `name` and `age`:
+Imagine we started implementing user objects using data properties `name` and `age`:
 
 ```js
 function User(name, age) {

1-js/08-prototypes/01-prototype-inheritance/2-search-algorithm/task.md

@@ -6,7 +6,7 @@ importance: 5
 
 The task has two parts.
 
-We have objects:
+Given the following objects:
 
 ```js
 let head = {

1-js/08-prototypes/01-prototype-inheritance/3-proto-and-this/task.md

@@ -2,7 +2,7 @@ importance: 5
 
 ---
 
-# Where it writes?
+# Where does it write?
 
 We have `rabbit` inheriting from `animal`.
 

1-js/08-prototypes/01-prototype-inheritance/4-hamster-proto/task.md

@@ -2,11 +2,11 @@ importance: 5
 
 ---
 
-# Why two hamsters are full?
+# Why are both hamsters full?
 
 We have two hamsters: `speedy` and `lazy` inheriting from the general `hamster` object. 
 
-When we feed one of them, the other one is also full. Why? How to fix it?
+When we feed one of them, the other one is also full. Why? How can we fix it?
 
 ```js run
 let hamster = {

1-js/08-prototypes/01-prototype-inheritance/article.md

@@ -34,7 +34,7 @@ rabbit.__proto__ = animal;
 ```smart header="`__proto__` is a historical getter/setter for `[[Prototype]]`"
 Please note that `__proto__` is *not the same* as `[[Prototype]]`. That's a getter/setter for it.
 
-It exists for historical reasons, in modern language it is replaced with functions `Object.getPrototypeOf/Object.setPrototypeOf` that also get/set the prototype. We'll study the reasons for that and these functions later.
+It exists for historical reasons. In modern language it is replaced with functions `Object.getPrototypeOf/Object.setPrototypeOf` that also get/set the prototype. We'll study the reasons for that and these functions later.
 
 By the specification, `__proto__` must only be supported by browsers, but in fact all environments including server-side support it. For now, as `__proto__` notation is a little bit more intuitively obvious, we'll use it in the examples.
 ```
@@ -203,7 +203,7 @@ Here in the line `(*)` the property `admin.fullName` has a getter in the prototy
 
 ## The value of "this"
 
-An interesting question may arise in the example above: what's the value of `this` inside `set fullName(value)`? Where the properties `this.name` and `this.surname` are written: into `user` or `admin`?
+An interesting question may arise in the example above: what's the value of `this` inside `set fullName(value)`? Where are the properties `this.name` and `this.surname` written: into `user` or `admin`?
 
 The answer is simple: `this` is not affected by prototypes at all.
 
@@ -246,13 +246,13 @@ The resulting picture:
 
 ![](proto-animal-rabbit-walk-3.svg)
 
-If we had other objects like `bird`, `snake` etc inheriting from `animal`, they would also gain access to methods of `animal`. But `this` in each method call would be the corresponding object, evaluated at the call-time (before dot), not `animal`. So when we write data into `this`, it is stored into these objects.
+If we had other objects, like `bird`, `snake`, etc., inheriting from `animal`, they would also gain access to methods of `animal`. But `this` in each method call would be the corresponding object, evaluated at the call-time (before dot), not `animal`. So when we write data into `this`, it is stored into these objects.
 
 As a result, methods are shared, but the object state is not.
 
 ## for..in loop
 
-The `for..in` loops over inherited properties too.
+The `for..in` loop iterates over inherited properties too.
 
 For instance:
 
@@ -267,7 +267,7 @@ let rabbit = {
 };
 
 *!*
-// Object.keys only return own keys
+// Object.keys only returns own keys
 alert(Object.keys(rabbit)); // jumps
 */!*
 

1-js/08-prototypes/02-function-prototype/1-changing-prototype/task.md

@@ -20,7 +20,7 @@ alert( rabbit.eats ); // true
 ```
 
 
-1. We added one more string (emphasized), what `alert` shows now?
+1. We added one more string (emphasized). What will `alert` show now?
 
     ```js
     function Rabbit() {}
@@ -54,7 +54,7 @@ alert( rabbit.eats ); // true
     alert( rabbit.eats ); // ?
     ```
 
-3. Like this (replaced one line)?
+3. And like this (replaced one line)?
 
     ```js
     function Rabbit() {}

1-js/08-prototypes/02-function-prototype/article.md

@@ -2,7 +2,7 @@
 
 Remember, new objects can be created with a constructor function, like `new F()`.
 
-If `F.prototype` is an object, then `new` operator uses it to set `[[Prototype]]` for the new object.
+If `F.prototype` is an object, then the `new` operator uses it to set `[[Prototype]]` for the new object.
 
 ```smart
 JavaScript had prototypal inheritance from the beginning. It was one of the core features of the language.
@@ -158,9 +158,9 @@ Rabbit.prototype = {
 
 In this chapter we briefly described the way of setting a `[[Prototype]]` for objects created via a constructor function. Later we'll see more advanced programming patterns that rely on it.
 
-Everything is quite simple, just few notes to make things clear:
+Everything is quite simple, just a few notes to make things clear:
 
-- The `F.prototype` property (don't mess with `[[Prototype]]`) sets `[[Prototype]]` of new objects when `new F()` is called.
+- The `F.prototype` property (don't mistake it for `[[Prototype]]`) sets `[[Prototype]]` of new objects when `new F()` is called.
 - The value of `F.prototype` should be either an object or `null`: other values won't work.
 -  The `"prototype"` property only has such a special effect when set on a constructor function, and invoked with `new`.
 

1-js/08-prototypes/03-native-prototypes/article.md

@@ -99,12 +99,12 @@ alert(f.__proto__.__proto__ == Object.prototype); // true, inherit from objects
 
 The most intricate thing happens with strings, numbers and booleans.
 
-As we remember, they are not objects. But if we try to access their properties, then temporary wrapper objects are created using built-in constructors `String`, `Number`, `Boolean`, they provide the methods and disappear.
+As we remember, they are not objects. But if we try to access their properties, temporary wrapper objects are created using built-in constructors `String`, `Number` and `Boolean`. They provide the methods and disappear.
 
 These objects are created invisibly to us and most engines optimize them out, but the specification describes it exactly this way. Methods of these objects also reside in prototypes, available as `String.prototype`, `Number.prototype` and `Boolean.prototype`.
 
 ```warn header="Values `null` and `undefined` have no object wrappers"
-Special values `null` and `undefined` stand apart. They have no object wrappers, so methods and properties are not available for them. And there are no corresponding prototypes too.
+Special values `null` and `undefined` stand apart. They have no object wrappers, so methods and properties are not available for them. And there are no corresponding prototypes either.
 ```
 
 ## Changing native prototypes [#native-prototype-change]
@@ -129,9 +129,9 @@ So, generally, modifying a native prototype is considered a bad idea.
 
 **In modern programming, there is only one case where modifying native prototypes is approved. That's polyfilling.**
 
-Polyfilling is a term for making a substitute for a method that exists in JavaScript specification, but is not yet supported by current JavaScript engine.
+Polyfilling is a term for making a substitute for a method that exists in the JavaScript specification, but is not yet supported by a particular JavaScript engine.
 
-Then we may implement it manually and populate the built-in prototype with it.
+We may then implement it manually and populate the built-in prototype with it.
 
 For instance:
 
@@ -144,7 +144,7 @@ if (!String.prototype.repeat) { // if there's no such method
 
     // actually, the code should be a little bit more complex than that
     // (the full algorithm is in the specification)
-    // but even an imperfect polyfill is often considered good enough for use
+    // but even an imperfect polyfill is often considered good enough
     return new Array(n + 1).join(this);
   };
 }
@@ -179,18 +179,18 @@ obj.join = Array.prototype.join;
 alert( obj.join(',') ); // Hello,world!
 ```
 
-It works, because the internal algorithm of the built-in `join` method only cares about the correct indexes and the `length` property, it doesn't check that the object is indeed the array. And many built-in methods are like that.
+It works because the internal algorithm of the built-in `join` method only cares about the correct indexes and the `length` property. It doesn't check if the object is indeed an array. Many built-in methods are like that.
 
 Another possibility is to inherit by setting `obj.__proto__` to `Array.prototype`, so all `Array` methods are automatically available in `obj`.
 
 But that's impossible if `obj` already inherits from another object. Remember, we only can inherit from one object at a time.
 
-Borrowing methods is flexible, it allows to mix functionality from different objects if needed.
+Borrowing methods is flexible, it allows to mix functionalities from different objects if needed.
 
 ## Summary
 
 - All built-in objects follow the same pattern:
-    - The methods are stored in the prototype (`Array.prototype`, `Object.prototype`, `Date.prototype` etc).
-    - The object itself stores only the data (array items, object properties, the date).
-- Primitives also store methods in prototypes of wrapper objects: `Number.prototype`, `String.prototype`, `Boolean.prototype`. Only `undefined` and `null` do not have wrapper objects.
-- Built-in prototypes can be modified or populated with new methods. But it's not recommended to change them. Probably the only allowable case is when we add-in a new standard, but not yet supported by the engine JavaScript method.
+    - The methods are stored in the prototype (`Array.prototype`, `Object.prototype`, `Date.prototype`, etc.)
+    - The object itself stores only the data (array items, object properties, the date)
+- Primitives also store methods in prototypes of wrapper objects: `Number.prototype`, `String.prototype` and `Boolean.prototype`. Only `undefined` and `null` do not have wrapper objects
+- Built-in prototypes can be modified or populated with new methods. But it's not recommended to change them. The only allowable case is probably when we add-in a new standard, but it's not yet supported by the JavaScript engine