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Author: iliakan

1-js/2-first-steps/19-function-expression/article.md

@@ -68,17 +68,40 @@ In more detail:
     Please note again: there are no brackets after `sayHi`. If they were, then `func = sayHi()` would write  *the result of the call* `sayHi()` into `func`, not *the function* `sayHi` itself.
 3. Now the function can be called both as `sayHi()` and `func()`.
 
-
 Note, that we could also have used a Function Expression to declare `sayHi`, in the first line: `let sayHi = function() { ... }`. Everything would work the same.
 
+Every value in Javascript has the type. What type of value is a function?
+
+**In Javascript, a function is an object.**
+
+We can abuse this by adding properties to it and using them in the code:
+
+```js run
+function sayHi() {
+  alert("Hi");
+  sayHi.counter++;
+}
+sayHi.counter = 0;
+
+sayHi(); // Hi 
+sayHi(); // Hi 
+
+alert( `Called ${sayHi.counter} times` ); // Called 2 times
+```
+
+There are many well-known Javascript libraries that make use of this. They create a function and attach many other functions to it as its properties. For instance, the [jquery](https://jquery.com) library creates a function named `$`, the library [lodash](https://lodash.com) creates a function `_`. So, we have something that can do the job by itself and also carries a bunch of other functionality.
+
+
 ```smart header="A function is a value representing an \"action\""
 Regular values like strings or numbers represent the *data*.
 
 A function can be perceived as an *action*.
 
-We can copy it between variables and run when we want.
+We can copy it between variables and run when we want. We can even add properties to it if we wish.
 ```
 
+
+
 ## Function Expression as a method
 
 Now let's go back: we have two ways of declaring a function. Do we really need both? What's about Function Expressions that makes it a good addition?

1-js/4-data-structures/2-number/article.md

@@ -327,18 +327,11 @@ Sometimes `isFinite` is used to validate the string value for being a regular nu
 ```js run
 let num = +prompt("Enter a number", '');
 
+// isFinite will be true only for regular numbers
 alert(`num:${num}, isFinite:${isFinite(num)}`);
 ```
 
-Here `num` is always of a number type, because of the unary plus `+`, but...
-
-- It may be `NaN` if the string is non-numeric. 
-- It may be `Infinity` if the user typed in `"Infinity"`.
-
-The `isFinite` test checks that and returns `true` only if it's a regular number. That's just what we usually need.
-
-Please note that an empty or a space-only string would give `num=0` in the described case. 
-
+Please note that an empty or a space-only string is treated as `0` in the described case. If it's not what's needed, then additional checks are required. 
 
 ## parseInt and parseFloat
 

1-js/4-data-structures/3-string/1-ucfirst/_js.view/test.js

@@ -1,9 +1,9 @@
 describe("ucFirst", function() {
-  it('делает первый символ заглавным', function() {
-    assert.strictEqual(ucFirst("вася"), "Вася");
+  it('Uppercases the first symbol', function() {
+    assert.strictEqual(ucFirst("john"), "John");
   });
 
-  it('для пустой строки возвращает пустую строку', function() {
+  it("Doesn't die on an empty string", function() {
     assert.strictEqual(ucFirst(""), "");
   });
 });

1-js/4-data-structures/3-string/1-ucfirst/solution.md

@@ -1,26 +1,27 @@
-Мы не можем просто заменить первый символ, т.к. строки в JavaScript неизменяемы.
+We can't "replace" the first character, because strings in JavaScript are immutable.
 
-Но можно пересоздать строку на основе существующей, с заглавным первым символом:
+But we can make a new string based on the existing one, with the uppercased first character:
 
 ```js
-var newStr = str[0].toUpperCase() + str.slice(1);
+let newStr = str[0].toUpperCase() + str.slice(1);
 ```
 
-Однако, есть небольшая проблемка -- в случае, когда строка пуста, будет ошибка.
+There's a small problem though. If `str` is empty, then `str[0]` is undefined, so we'll get an error.
 
-Ведь `str[0] == undefined`, а у `undefined` нет метода `toUpperCase()`.
+There are two variants here:
 
-Выхода два. Первый -- использовать `str.charAt(0)`, он всегда возвращает строку, для пустой строки -- пустую, но не `undefined`. Второй -- отдельно проверить на пустую строку, вот так:
+1. Use `str.charAt(0)`, as it always returns a string (maybe empty).
+2. Add a test for an empty string.
+
+Here's the 2nd variant:
 
 ```js run
 function ucFirst(str) {
-  // только пустая строка в логическом контексте даст false
   if (!str) return str;
 
   return str[0].toUpperCase() + str.slice(1);
 }
 
-alert( ucFirst("вася") );
+alert( ucFirst("john") ); // John
 ```
 
-P.S. Возможны и более короткие решения, использующие методы для работы со строками, которые мы пройдём далее.

1-js/4-data-structures/3-string/1-ucfirst/task.md

@@ -2,13 +2,11 @@ importance: 5
 
 ---
 
-# Сделать первый символ заглавным
+# Uppercast the first character
 
-Напишите функцию `ucFirst(str)`, которая возвращает строку `str` с заглавным первым символом, например:
+Write a function `ucFirst(str)` that returns the string `str` with the uppercased first character, for instance:
 
 ```js
-ucFirst("вася") == "Вася";
-ucFirst("") == ""; // нет ошибок при пустой строке
+ucFirst("john") == "John";
 ```
 
-P.S. В JavaScript нет встроенного метода для этого. Создайте функцию, используя  `toUpperCase()` и `charAt()`.

1-js/4-data-structures/3-string/2-check-spam/_js.view/solution.js

@@ -1,5 +1,5 @@
 function checkSpam(str) {
-  var lowerStr = str.toLowerCase();
+  let lowerStr = str.toLowerCase();
 
-  return !!(~lowerStr.indexOf('viagra') || ~lowerStr.indexOf('xxx'));
+  return lowerStr.includes('viagra') || lowerStr.includes('xxx');
 }

1-js/4-data-structures/3-string/2-check-spam/_js.view/test.js

@@ -1,13 +1,13 @@
 describe("checkSpam", function() {
-  it('считает спамом "buy ViAgRA now"', function() {
+  it('finds spam in "buy ViAgRA now"', function() {
     assert.isTrue(checkSpam('buy ViAgRA now'));
   });
 
-  it('считает спамом "free xxxxx"', function() {
+  it('finds spam in "free xxxxx"', function() {
     assert.isTrue(checkSpam('free xxxxx'));
   });
 
-  it('не считает спамом "innocent rabbit"', function() {
+  it('no spam in "innocent rabbit"', function() {
     assert.isFalse(checkSpam('innocent rabbit'));
   });
 });

1-js/4-data-structures/3-string/2-check-spam/solution.md

@@ -1,12 +1,10 @@
-Метод `indexOf` ищет совпадение с учетом регистра. То есть, в строке `'xXx'` он не найдет `'XXX'`.
-
-Для проверки приведем к нижнему регистру и строку `str` а затем уже будем искать.
+To make the search case-insensitive, let's bring the stirng to lower case and then search:
 
 ```js run
 function checkSpam(str) {
-  var lowerStr = str.toLowerCase();
+  let lowerStr = str.toLowerCase();
 
-  return !!(~lowerStr.indexOf('viagra') || ~lowerStr.indexOf('xxx'));
+  return lowerStr.includes('viagra') || lowerStr.includes('xxx');
 }
 
 alert( checkSpam('buy ViAgRA now') );

1-js/4-data-structures/3-string/2-check-spam/task.md

@@ -2,11 +2,11 @@ importance: 5
 
 ---
 
-# Проверьте спам
+# Check for spam
 
-Напишите функцию `checkSpam(str)`, которая возвращает `true`, если строка `str` содержит 'viagra' or 'XXX', а иначе `false`.
+Write a function `checkSpam(str)` that returns `true` if `str` contains 'viagra' or 'XXX', otherwise `false.
 
-Функция должна быть нечувствительна к регистру:
+The function must be case-insensitive:
 
 ```js
 checkSpam('buy ViAgRA now') == true

1-js/4-data-structures/3-string/3-truncate/_js.view/solution.js

@@ -1,4 +1,4 @@
 function truncate(str, maxlength) {
-  return (str.length > maxlength) ?
-    str.slice(0, maxlength - 3) + '...' : str;
+  return (str.length > maxlength) ? 
+    str.slice(0, maxlength - 1) + '…' : str;
 }