chapter 3 review

Author: loiane

src/03-array/01-arrays.js

@@ -28,34 +28,36 @@ console.log('averageTemp[3]', averageTemp[3]);
 console.log('averageTemp[4]', averageTemp[4]);
 
 /* Creating and initializing arrays */
-let daysOfWeek = new Array(); // {1}
-daysOfWeek = new Array(7); // {2}
-daysOfWeek = new Array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'); // {3}
-
 // preferred
-daysOfWeek = []; // {4}
-daysOfWeek = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']; // {5}
+let daysOfWeek = []; // creates an empty array
+daysOfWeek = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
+
+console.log('daysOfWeek.length:', daysOfWeek.length); // daysOfWeek.length: 7
 
-console.log('daysOfWeek.length', daysOfWeek.length); // output: 7
+// different syntax, avoid:
+daysOfWeek = new Array(); // creates an empty array
+daysOfWeek = new Array(7); // pre-defined length of 7 
+daysOfWeek = new Array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday');
 
+// ---- interating over arrays ----
 for (let i = 0; i < daysOfWeek.length; i++) {
   console.log(`daysOfWeek[${i}]`, daysOfWeek[i]);
 }
 
 /* fibonacci numbers */
 // Fibonacci: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...
-const fibonacci = []; // {1}
-fibonacci[1] = 1; // {2}
-fibonacci[2] = 1; // {3}
+const fibonacci = [];
+fibonacci[0] = 0; 
+fibonacci[1] = 1; 
 
-// create the fibonacci sequence starting from the 3rd element
-for (let i = 3; i < 20; i++) {
-  fibonacci[i] = fibonacci[i - 1] + fibonacci[i - 2]; // //{4}
+// create the fibonacci sequence starting from the 2nd element
+for (let i = 2; i < 20; i++) {
+  fibonacci[i] = fibonacci[i - 1] + fibonacci[i - 2]; 
 }
 
 // display the fibonacci sequence
-for (let i = 1; i < fibonacci.length; i++) { // {5}
-  console.log(`fibonacci[${i}]`, fibonacci[i]); // {6}
+for (let i = 1; i < fibonacci.length; i++) {
+  console.log(`fibonacci[${i}]`, fibonacci[i]);
 }
 
 // instead of {5} and {6} we can use

src/03-array/02-adding-removing-elements.js

@@ -1,73 +1,81 @@
 // Path: src/03-array/02-adding-removing-elements.js
 
 // @ts-ignore
-let numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+let raffleTickets = [5, 6, 7, 8, 9];
 
-numbers[numbers.length] = 10;
+raffleTickets[raffleTickets.length] = 10;
 
 // using push method
-numbers.push(11);
-numbers.push(12, 13);
+raffleTickets.push(11);
+console.log(raffleTickets.push(12, 13)); // 9
+
+console.log('raffleTickets: ', raffleTickets); // raffleTickets:  [ 5, 6, 7, 8, 9, 10, 11, 12, 13 ]
 
 // inserting elements at the beginning
-// @ts-ignore
-Array.prototype.insertAtBeginning = function (value) {
-    for (let i = this.length; i >= 0; i--) {
-        this[i] = this[i - 1];
+const insertAtBeginning = function (array, value) {
+    for (let i = array.length; i >= 0; i--) {
+        array[i] = array[i - 1];
     }
-    this[0] = value;
+    array[0] = value;
+    return array;
 };
-// @ts-ignore  
-numbers.insertAtBeginning(-1);
+raffleTickets = insertAtBeginning(raffleTickets, 4);
+console.log('raffleTickets: ', raffleTickets); // raffleTickets:  [ 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 ]
 
 // using unshift method
-numbers.unshift(-2);
-numbers.unshift(-4, -3);
+raffleTickets.unshift(3);
+raffleTickets.unshift(0, 1, 2); 
+
+console.log('raffleTickets: ', raffleTickets); // raffleTickets:  [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 ]
 
 // removing elements from the end
-numbers.pop(); // number 13 is removed
-// console.log('Removed element: ', numbers.pop()); // Removed element:  13
-console.log('array length: ', numbers.length); // array length:  17
+let winningTicket = raffleTickets.pop(); 
+console.log('The winning ticket is:', winningTicket); // The winning ticket is: 13
+
+console.log('raffleTickets: ', raffleTickets); // raffleTickets:  [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]
+console.log('array length: ', raffleTickets.length); // array length:  13
 
 // removing elements from the beginning
-for (let i = 0; i < numbers.length; i++) {
+for (let i = 0; i < raffleTickets.length; i++) {
     // numbers[i] = numbers[i + 1];  
 }
 
 // removing elements from the beginning - educational purposes only
-// @ts-ignore
-Array.prototype.reIndex = function (myArray) {
-    const newArray = [];
-    for (let i = 0; i < myArray.length; i++) {
-        if (myArray[i] !== undefined) {
-            newArray.push(myArray[i]);
-        }
+const removeFirstElement = function(array) {
+    for (let i = 1; i < array.length; i++) {
+        array[i - 1] = array[i];
     }
-    return newArray;
+    array.length--;
+    return array;
 }
-// remove first position manually and reIndex 
-// @ts-ignore 
-Array.prototype.removeFromBeginning = function () {
-    for (let i = 0; i < this.length; i++) {
-        this[i] = this[i + 1];
+  
+// Apply to our raffleTickets array
+raffleTickets = removeFirstElement(raffleTickets); 
+console.log('Updated raffleTickets:', raffleTickets); // Updated raffleTickets: [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]
+console.log('array length: ', raffleTickets.length); // array length:  12
+
+// alternative way to remove elements from the beginning using a new array
+const removeFirstElementWithNewArray = function(array) {
+    let newArray = [];
+    for (let i = 1; i < array.length; i++) {
+        newArray.push(array[i]);
     }
-    // @ts-ignore
-    return this.reIndex(this);
-};
-// @ts-ignore
-// numbers = numbers.removeFromBeginning();
+    return newArray;
+}
 
 // using shift method
-numbers.shift();
-console.log('numbers after shift: ', numbers);
-console.log('array length: ', numbers.length); // array length:  16
+raffleTickets.shift();
+console.log('numbers after shift: ', raffleTickets); // numbers after shift:  [ 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]
+console.log('array length: ', raffleTickets.length); // array length:  11
 
 // adding and removing elements from a specific position
-// using the splice method
-numbers.splice(5, 3); // removes 3 elements starting from the 5th position
-console.log('numbers: ', numbers); // numbers:  [ -3, -2, -1, 0, 1, 5, 6, 7, 8, 9, 10, 11, 12 ] 
+// using the splice method to remove elements
+const prizeWinners = raffleTickets.splice(5, 3); // removes 3 elements starting from the 5th position
+console.log('prizeWinners: ', prizeWinners); // prizeWinners:  [ 7, 8, 9 ]
+console.log('remaing tickets: ', raffleTickets); // remaing tickets:  [ 2, 3, 4, 5, 6, 10, 11, 12 ]
 
-// adding elements, 2, 3 and 4 at the 5th position
-numbers.splice(5, 0, 2, 3, 4);
+// adding number 8 and 9 back to the array
+raffleTickets.splice(5, 0, 8, 9); // adds 8, 9 back to the array
+console.log('raffleTickets: ', raffleTickets); // raffleTickets:  [ 2, 3, 4, 5, 6, 8, 9, 10, 11, 12 ]
 
 // to see the output of this file use the command: node src/03-array/02-adding-removing-elements.js

src/03-array/03-iterator-functions.js

@@ -1,45 +1,85 @@
 // Path: src/03-array/03-iterator-functions.js
 
-// @ts-ignore
-const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-
 // using forEach method
-numbers.forEach((value, index) => {
-  console.log(`numbers[${index}]`, value);
-});
+const raffleParticipants = ['[email protected]', '[email protected]', '[email protected]'];
+const sendWelcomeEmail = email => {
+  console.log(`Welcome email sent to ${email}`);
+};
+
+raffleParticipants.forEach(email => sendWelcomeEmail(email));
+
+raffleParticipants.forEach(sendWelcomeEmail);
+
+const sendConfirmationEmail = (email, raffleNumber) => {
+  console.log(`Hi ${email}, your raffle number is ${raffleNumber}`);
+};
 
-numbers.forEach(value => console.log(value));
+const sendSpecialPrizeEmail = (email) => {
+  console.log(`Congrats ${email}! You've won a special prize!`);
+};
+
+raffleParticipants.forEach((value, index, array) => {
+  const raffleNumber = index + 1; // Raffle numbers start from 1
+  sendConfirmationEmail(value, raffleNumber);
+
+  if (index === array.length - 1) { // Check if it's the last element
+      sendSpecialPrizeEmail(value);
+  }
+});
 
 // using every method
-const isBelowSeven = numbers.every(value => value < 7);
-console.log('All values are below 7?:', isBelowSeven); // false
-
-// rewriting the preceding code using for loop
-let isBelowSevenForLoop = true;
-for (let i = 0; i < numbers.length; i++) {
-  if (numbers[i] >= 7) {
-    isBelowSevenForLoop = false;
-    break;
+const formFields = [
+  { id: 'username', value: 'poppy' }, 
+  { id: 'email', value: '[email protected]' },
+  { id: 'password', value: 'bookClub123!' }];
+
+  const isFormValid = () => 
+    formFields.every(field => field.value !== '' && field.value !== null); 
+
+
+const onFormSubmit = () => {
+  if (isFormValid()) {
+    console.log('Form submitted successfully!');
+  } else {
+    console.log('Please fill out all required fields.');
   }
 }
-console.log('All values are below 7?:', isBelowSevenForLoop); // false
+onFormSubmit(); // Form submitted successfully!
+
+// using a for loop
+const isFormValidForLoop = () => {
+  for (let i = 0; i < formFields.length; i++) {
+    if (formFields[i].value === '' || formFields[i].value === null) {
+      return false;
+    }
+  }
+  return true;
+};
+
 
 // using some method
-const isSomeValueBelowSeven = numbers.some(value => value < 7);
-console.log('Is any value below 7?:', isSomeValueBelowSeven); // true
-
-// rewriting the preceding code using for loop
-let isSomeValueBelowSevenForLoop = false;
-for (let i = 0; i < numbers.length; i++) {
-  if (numbers[i] < 7) {
-    isSomeValueBelowSevenForLoop = true;
-    break;
+const products = [
+  { name: 'Laptop', inStock: true },
+  { name: 'Smartphone', inStock: false },
+  { name: 'Headphones', inStock: true }
+];
+
+const searchQuery = 'phone';
+const isProductAvailable = products.some(product => {
+  return product.name.toLowerCase().includes(searchQuery.toLowerCase()) && product.inStock;
+});
+
+console.log(isProductAvailable ? 'Product Available!' : 'No Products Found.'); // Product Available!
+
+// using a for loop
+const isProductAvailableForLoop = () => {
+  for (let i = 0; i < products.length; i++) {
+    if (products[i].name.toLowerCase().includes(searchQuery.toLowerCase()) && products[i].inStock) {
+      return true; // Found a match, no need to continue checking
+    }
   }
-}
+  return false; // No match found after checking all products
+};
 
-// using filter method
-// @ts-ignore
-const valuesBelowSeven = numbers.filter(value => value < 7);
-console.log('Values below 7:', valuesBelowSeven); // [1, 2, 3, 4, 5, 6]
 
 // to see the output of this file use the command: node src/03-array/03-iterator-functions.js