chapter 1: code updated due to review

Author: loiane

src/01-intro/01-hello-variables.js

@@ -4,30 +4,52 @@
 console.log('Hello, World!');
 
 // variables
-var num = 1; // {1}
-num = 3; // {2}
+var num = 1; 
+num = 'one' ; 
 
-let myVar = 2; // {3}
-myVar = 4; // {4}
+let myVar = 2; 
+myVar = 4; 
 
-const price = 1.5; // {5} number
-const publisher = 'Packt'; // {6} string
-const javaScriptBook = true; // {7} boolean
-const nullVar = null; // {8} null
-let und; // {9} undefined
+const price = 1.5; // number
+const publisher = 'Packt'; // string
+const javaScriptBook = true; // boolean
+const nullVar = null; // null
+let und; // undefined
 
-console.log('num: ' + num);
-console.log('myVar: ' + myVar);
+console.log('price: ' + price); 
 console.log('publisher: ' + publisher);
 console.log('javaScriptBook: ' + javaScriptBook);
-console.log('price: ' + price);
 console.log('nullVar: ' + nullVar);
 console.log('und: ' + und);
 
+console.log('**** Data types ****');
+
+console.log('typeof price: ', typeof price); // number
+console.log('typeof publisher: ', typeof publisher); // string
+console.log('typeof javaScriptBook: ', typeof javaScriptBook); // boolean
+console.log('typeof nullVar: ', typeof nullVar); // object
+console.log('typeof und: ', typeof und); // undefined
+
 const book = {
-  title: 'Data Structures and Algorithms', // {10}
+  title: 'Data Structures and Algorithms', 
 }
-book.title = 'Data Structures and Algorithms in JavaScript'; // {11}
-// book = { anotherTitle: 'Data Structures’ } // this will not work {12}
+
+console.log('book title: ', book.title);
+
+book.title = 'Data Structures and Algorithms in JavaScript'; 
+// book = { anotherTitle: 'Data Structures’ } // this will not work
+
+// reassignment of objects:
+let book2 = {
+  title: 'Data Structures and Algorithms', 
+}
+book2 = { title: 'Data Structures' };
+
+// symbol
+const title = Symbol('title');
+const book3 = {
+  [title]: 'Data Structures and Algorithms'
+};
+console.log(book3[title]); // Data Structures and Algorithms
 
 // to see the output of this file use the command: node src/01-intro/01-hello-variables.js

src/01-intro/02-conditionals.js

@@ -18,6 +18,9 @@ if (number === 1) {
 // is the same as
 number === 1 ? number-- : number++;
 
+// is the same as
+number = number === 1 ? number - 1 : number + 1;
+
 /* Example 03 - if-else-if-else... */
 let month = 5;
 if (month === 1) {

src/01-intro/04-functions.js

@@ -11,7 +11,7 @@ function sum(num1, num2) {
     return num1 + num2;
 }
 
-var result = sum(1, 2);
+const result = sum(1, 2);
 console.log(result); // outputs 3
 
 /* function with default parameter */

src/01-intro/05-scope.js

@@ -1,34 +1,39 @@
 // Path: src/01-intro/05-scope.js
 
-let movie = 'Lord of the Rings'; // {1}
+let movie = 'Lord of the Rings';
 
 function starWarsFan() {
-  const movie = 'Star Wars'; // {2}
+  const movie = 'Star Wars'; 
   return movie;
 }
 
 function marvelFan() {
-  movie = 'The Avengers'; // {3}
+  movie = 'The Avengers'; 
   return movie;
 }
 
+console.log(movie); // Lord of the Rings
+console.log(starWarsFan()); // Star Wars
+console.log(marvelFan()); // The Avengers
+console.log(movie); // The Avengers
+
+// block scope
 function blizzardFan() {
   const isFan = true;
-  let phrase = 'Warcraft'; // {4}
+  let phrase = 'Warcraft'; 
   console.log('Before if: ' + phrase);
   if (isFan) {
-    let phrase = 'initial text'; // {5}
-    phrase = 'For the Horde!'; // {6}
+    let phrase = 'initial text'; 
+    phrase = 'For the Horde!'; 
     console.log('Inside if: ' + phrase);
   }
-  phrase = 'For the Alliance!'; // {7}
+  phrase = 'For the Alliance!'; 
   console.log('After if: ' + phrase);
 }
 
-console.log(movie); // Lord of the Rings
-console.log(starWarsFan()); // Star Wars
-console.log(marvelFan()); // The Avengers
-console.log(movie); // The Avengers
-blizzardFan(); // Before if: Warcraft, Inside if: For the Horde!, After if: For the Alliance!
+blizzardFan(); 
+// Before if: Warcraft
+// Inside if: For the Horde!
+// After if: For the Alliance!
 
 // to see the output of this file use the command: node src/01-intro/05-scope.js

src/01-intro/06-objects.js

@@ -15,24 +15,24 @@ obj = {
 /* Class example */
 class Book {
 
-  #percentagePerSale = 0.12; // {1}
+  #percentagePerSale = 0.12; 
 
   constructor(title, pages, isbn) { 
-    this.title = title; // {2}
+    this.title = title;
     this.pages = pages;
     this.isbn = isbn;
   }
 
-  get price() { // {3}
+  get price() {
     return this.pages * this.#percentagePerSale;
   }
 
-  static copiesSold = 0; // {4}
-  static sellCopy() { // {5}
+  static copiesSold = 0; 
+  static sellCopy() {
     this.copiesSold++;
   }
 
-  printIsbn() { // {6}
+  printIsbn() {
     console.log(this.isbn);
   }
 }
@@ -52,13 +52,22 @@ console.log(Book.copiesSold); // 1
 Book.sellCopy();
 console.log(Book.copiesSold); // 2
 
-class Ebook extends Book { // {7}
+class Ebook extends Book { 
   constructor(title, pages, isbn, format) {
-    super(title, pages, isbn); // {8}
-    this.format = format; // {9}
+    super(title, pages, isbn); 
+    this.format = format; 
+  }
+  printIsbn() {
+    console.log('Ebook ISBN:',this.isbn);
   }
 }
-Ebook.sellCopy(); // {10}
-console.log(Ebook.copiesSold); // {11} 3
+Ebook.sellCopy();
+console.log(Ebook.copiesSold); // 3
+
+const myBook = new Book('title', 400, 'isbn');
+myBook.printIsbn(); // isbn
+const myEbook = new Ebook('Data Structures Ebook', 400, 'isbn 123', 'pdf');
+myEbook.printIsbn(); // Ebook ISBN: isbn 123
+
 
 // to see the output of this file use the command: node src/01-intro/06-objects.js