London | 25-ITP-Sep | Zadri Abdule | Sprint 2 | Module-Structuring-and-Testing-Data

Sprint-1/1-key-exercises/1-count.js

@@ -4,3 +4,4 @@ count = count + 1;
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
 // Describe what line 3 is doing, in particular focus on what = is doing
+// The = sign means assignment. It takes whatever is on the right side, works it out, and then stores that result into a variable on the left. So count = count + 1 means take the current value of count, add 1, and then save that back into count.

Sprint-1/1-key-exercises/2-initials.js

@@ -5,7 +5,9 @@ let lastName = "Johnson";
 // Declare a variable called initials that stores the first character of each string.
 // This should produce the string "CKJ", but you must not write the characters C, K, or J in the code of your solution.
 
-let initials = ``;
+let initials = firstName.charAt(0) + middleName.charAt(0) + lastName.charAt(0);
+
+console.log(initials);
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 

Sprint-1/1-key-exercises/3-paths.js

@@ -17,7 +17,10 @@ console.log(`The base part of ${filePath} is ${base}`);
 // Create a variable to store the dir part of the filePath variable
 // Create a variable to store the ext part of the variable
 
-const dir = ;
-const ext = ;
+const dir = filePath.slice(0, lastSlashIndex);
+const ext = base.slice(lastDotIndex);
+
+console.log(`The dir part of ${filePath} is ${dir}`);
+console.log(`The ext part of ${filePath} is ${ext}`);
 
 // https://www.google.com/search?q=slice+mdn

Sprint-1/1-key-exercises/4-random.js

@@ -2,8 +2,16 @@ const minimum = 1;
 const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+console.log(num);
 
 // In this exercise, you will need to work out what num represents?
 // Try breaking down the expression and using documentation to explain what it means
 // It will help to think about the order in which expressions are evaluated
 // Try logging the value of num and running the program several times to build an idea of what the program is doing
+
+// Math.random() returns a random decimal number between 0 and 1
+// (maximum - minimum + 1) represents the size of range of numbers we want to include. We add +1 because both minim and maximum are included in the range
+// Math.random() * (maximum - minimum + 1) gives us a random decimal between 0 and 100, but still decimal
+// Math.floor() rounds down to the nearest whole number. So this. turns decimals like 99.9 into 99
+// + minimum since minimum = 1, this shifts the entire random range up by 1. so instead of 0-100, the range becomes 1-100
+// num should return a random integer between 1 and 100

Sprint-1/2-mandatory-errors/0.js

@@ -1,2 +1,3 @@
 This is just an instruction for the first activity - but it is just for human consumption
-We don't want the computer to run these 2 lines - how can we solve this problem?
+We don't want the computer to run these 2 lines - how can we solve this problem? 
+// Using // to make them comments should resolve the problem. The // tells JavaScript to skip that line completely

Sprint-1/2-mandatory-errors/1.js

@@ -1,4 +1,12 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+const { cityOfBirth } = require("./2");
+
+let age = 33;
 age = age + 1;
+console.log(age);
+// Currently trying to print the string "I was born in Bolton" but it isn't working...
+// what's the error ?
+console.log(`I was born in ${cityOfBirth}`);
+
+// Changed const to let because the variables value need to change during the program. const creates a fixed reference that cannot be reassigned. but let allows updating the variable which is required when incrementing or modifying values.

Sprint-1/2-mandatory-errors/2.js

@@ -3,3 +3,4 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+// Error: Cannot access 'cityOfBirth' before instialization - the error means: you tried to use a let or const variable before its declaration line ran.

Sprint-1/2-mandatory-errors/3.js

@@ -1,9 +1,13 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working
 // Before running the code, make and explain a prediction about why the code won't work
 // Then run the code and see what error it gives.
 // Consider: Why does it give this error? Is this what I predicted? If not, what's different?
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value
+
+// I predict that the code will fail because .slice() is not valid on a number - The variable is a number, but .slice() only works on strings and arrays.
+// The error that I got is similar to what I had predicted.

Sprint-1/2-mandatory-errors/4.js

@@ -1,2 +1,13 @@
 const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+// This line of code attempts to declare a constant variable named 12HourClockTime, but it results in a syntax error
+const 24hourClockTime = "08:53";
+
+// While testing the code, the following error appeared in console:
+// SyntaxError: Invalid or unexpected token
+
+// Why did this error occur? according to the MDN Web Docs: https://developer.mozilla.org/en-US/docs , a "SyntaxError: Invalid or unexpected token" occurs when JavaScript encounters code that doesn't follow proper syntax rules
+// In this case, the error happens because JavaScript does not allow variable names to start with numbers. Variable names (also called identifiers) must begin with a letter, underscore (_), or dollar sign ($)
+
+// How to fix the error:
+const hour12ClockTime = "20:53";
+// These version follow JavaScript naming rules and will execute without errors

Sprint-1/3-mandatory-interpret/1-percentage-change.js

@@ -13,10 +13,25 @@ console.log(`The percentage change is ${percentageChange}`);
 
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
 
+// Line 4 contains two function calls: replaceAll(",", "") & Number(...)
+// Line 5 also contains two function calls: replaceAll(",","") & Number(...)
+// Line 10 contains one function call: console.log()
+
 // b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem?
 
+// The error originates from line 5: SyntaxError: missing ) after argument list. According to MDN Web Docs, this occurs when there is a problem with how a function is called - typically caused by a typo, a missing separator (such as a comma), or an incorrectly formatted string within the argument list
+
 // c) Identify all the lines that are variable reassignment statements
+// Line 4: Reassignment (not a declaration)
+// Line 5: Reassignment (not a declaration)
 
 // d) Identify all the lines that are variable declarations
+// Line 1: Variable declaration using 'let'
+// Line 2: Variable declaration using 'let'
+// Line 7: Variable declaration using 'const'
+// Line 8: Variable declaration using 'const'
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+/* The expression Number(carPrice.replaceAll(",","")) first uses the String.prototype.replaceAll() method to remove all commas from the string stored in carPrice
+It then passes the resulting string to the Number() function, which converts it into a numeric value. According to MDN, replaceALL() returns a new string with all occurrences of a 
+specified substring replaced, and Number() converts its argument to a number or return NaN if the conversion fails */

Sprint-1/3-mandatory-interpret/2-time-format.js

@@ -12,14 +12,28 @@ console.log(result);
 // For the piece of code above, read the code and then answer the following questions
 
 // a) How many variable declarations are there in this program?
+// There are 6 variable declarations in this program: movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours, and result
 
 // b) How many function calls are there?
+// There is only one function call in this program: console.log(results);
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// The expression movieLength % 60 uses the remainder operator ( % ) to work out how many seconds are left over after dividing the total movie length by 60.
+// So if movieLength is 8784 seconds, dividing by 60 gives 146 full minutes with 24 seconds left - that leftover part (24) is what this expression returns.
+// According to MDN Docs, the remainder operator gives the value that's left after one number is divided by another
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// The expression totalMinutes is a variable that stores the result of the calculation (movieLength - remainingSeconds) / 60. It represents the total number of full minutes in the movie after converting the total seconds into minutes. 
+// According to MDN Docs, a variable is a named container used to store data values. In this cause, totalMinutes holds a numeric value that JavaScript can use later in other calculations, like finding the number of hours or remaining minutes.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// The variable result stores a formatted string that combines the total hours, remaining minutes, and remaining seconds into one readable time format.
+// It uses template literals (the backtick syntax `...`) to insert each variable's value directly into the string using ${} placeholders.
+// so, for example, if totalHours = 2, remainingMinutes = 26, and remainingSeconds = 24, the value of result becomes the string "2 : 26 : 24". 
+// According to MDN Docs, template literals allow embedded expressions inside strings, making it easier to create dynamic text
+// A better name for the variable result would be formattedTime because it makes it clearer what the value actually represents. Moreover, using a name like formattedTime makes the code easier to read and understand
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// This code works properly for positive whole numbers because the reminder ( % ) and division ( / ) operators correctly split the total number of seconds into hours, minutes, and seconds. 
+// However, it might not give the right results if movieLength is negative, a decimal, or not a number at all. As explained on MDN Docs, the remainder operator keeps the same sign as the left number, so if the input is negative, you would get negative remainders - which wouldn't make sense when showing time

Sprint-1/3-mandatory-interpret/3-to-pounds.js

@@ -25,3 +25,10 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 3. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length -1);
+// creates a new string that removes the last character ("p") from penceString, leaving just the number part
+// 8. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// Adds zero to the start of thr string if it's shorter than three digits, ensuring values like "9" become "009"
+// 14. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length -2)
+//.padEnd(2, "0") - Takes the last two digits as the pence portion of the price and adds a zero if it's missing a digit
+// 18. console.log(`£${pounds}.${pence}`) - Displays the formatted price in pounds and pence, such as £3.99

Sprint-2/1-key-errors/0.js

@@ -1,5 +1,6 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// It will show an error message
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
@@ -8,6 +9,13 @@ function capitalise(str) {
   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
+capitalise("Hello");
 
 // =============> write your explanation here
+// SyntaxError: Identifier 'str' has already been declared - This error means that the variable 'str' was declared more than once in the same scope.
+// JavaScrip doesn't allow that - once a variable name is declared with let or const, you can't declare it again.
 // =============> write your new code here
+function capitalise(str) {
+  return str[0].toUpperCase() + str.slice(1);
+}
+

Sprint-2/1-key-errors/1.js

@@ -2,19 +2,35 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// I predict that this program will throw a error - due to the variable decimalNumber being redeclared.
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
+/* function convertToPercentage(decimalNumber) {
   const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
 
   return percentage;
 }
 
-console.log(decimalNumber);
+console.log(decimalNumber); */
 
 // =============> write your explanation here
+// Function covertToPercentage(decimalNumber) - it has a parameter named decimalNumber
+// Inside the function: const decimalNumber =0.5; - this redeclares the same variable name that's already used for the parameter.
+// That causes an error: SyntaxError: Identifier 'decimalNumber' has already been declared - because you can't declare a const (or let) with the same name as a parameter inside the same function scope.
+// JavaScript doesn't allow us to declare a new variable with the same name in the same scope, so it caused an error.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+console.log(convertToPercentage(0.5));
+
+// Function decimalNumber = 0.5
+// It calculates 0.5 * 100 = 50
+// it returns "50%"
+// console logs 50%

Sprint-2/1-key-errors/2.js

@@ -4,17 +4,19 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
-
-function square(3) {
-    return num * num;
-}
+// It throw a error - because of invalid parameter (can't use a number as a parameter name)
+//function square(3) {
+ //   return num * num;
+//}
 
 // =============> write the error message here
-
+// SyntaxError: Unexpected number
 // =============> explain this error message here
-
+// The "Unexpected number" error arises when a numeral is improperly positioned or used within JavaScript code.
 // Finally, correct the code to fix the problem
-
 // =============> write your new code here
+function square(num){
+    return num * num;
+}
 
-
+console.log(square);

Sprint-2/2-mandatory-debug/0.js

@@ -1,14 +1,20 @@
 // Predict and explain first...
 
 // =============> write your prediction here
-
+// It will throw a undefined error
 function multiply(a, b) {
   console.log(a * b);
 }
 
-console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
+//console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`); 
 
 // =============> write your explanation here
+// The function printed the answer but didn't return it, so when it was used in the  template string, it came out as "undefined."
 
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+function multiply(a, b) {
+  return a * b;
+}
+
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);

Sprint-2/2-mandatory-debug/1.js

@@ -1,13 +1,20 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// I predict it will throw a undefined error
 
-function sum(a, b) {
+/* function sum(a, b) {
   return;
   a + b;
 }
 
-console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+console.log(`The sum of 10 and 32 is ${sum(10, 32)}`); */
 
 // =============> write your explanation here
+// The problem was that the semicolon after return, which made the function stop before adding the numbers.
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+function sum(a, b) {
+  return a + b; // Once I put a + b on the same line as return, it worked
+}
+
+console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);

Sprint-2/2-mandatory-debug/2.js

@@ -2,6 +2,7 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// Since getLastDigit() does not declare any parameters, the arguments passed when calling it are going to be ignored
 
 const num = 103;
 
@@ -15,10 +16,25 @@ console.log(`The last digit of 806 is ${getLastDigit(806)}`);
 
 // Now run the code and compare the output to your prediction
 // =============> write the output here
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
 // Explain why the output is the way it is
 // =============> write your explanation here
+// The function getLastDigit() does not any parameters, but it is being called with argument:
+// getLastDigit(42), getLastDigit(105), and getLastDigit(806). Inside the function, it always uses the global const num, which is set to 103.
+// That means every call ignores the arguments and always returns the last digit of 103, which is "3"
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+ function getLastDigit(num){
+  return num.toString().slice(-1);
+
+}
+
+console.log(`The last digit of 42 is ${getLastDigit(42)}`);
+console.log(`The last digit of 105 is ${getLastDigit(105)}`);
+console.log(`The last digit of 806 is ${getLastDigit(806)}`);
+
 
 // This program should tell the user the last digit of each number.
 // Explain why getLastDigit is not working properly - correct the problem

Sprint-2/3-mandatory-implement/1-bmi.js

@@ -16,4 +16,12 @@
 
 function calculateBMI(weight, height) {
     // return the BMI of someone based off their weight and height
-}
+    const bmi = weight / (height * height);
+    return bmi.toFixed(1);
+}
+
+console.log(`Your BMI is ${calculateBMI(68, 1.75)}`);
+// How it works: function calculateBMI(weight, height)
+// Parameters: weight - number, person's weight in kilograms height - number, person's height in meters
+// Returns: The Body Mass Index (BMI), rounded to one decimal place
+

Sprint-2/3-mandatory-implement/2-cases.js

@@ -14,3 +14,6 @@
 // You will need to come up with an appropriate name for the function
 // Use the MDN string documentation to help you find a solution
 // This might help https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase
+ const greeting = "Hello there."
+
+ console.log(greeting.toUpperCase());

Sprint-2/3-mandatory-implement/3-to-pounds.js

@@ -4,3 +4,16 @@
 // You will need to declare a function called toPounds with an appropriately named parameter.
 
 // You should call this function a number of times to check it works for different inputs
+funnction formatPenceToPounds(penceString) {
+
+    const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+
+    const pounds = paddedPenceNumberString.slice(0, -2);
+    const pence = paddedPenceNumberString.slice(-2);
+
+    return `£${pounds}.${pence}`;
+}
+
+console.log(formatPenceToPounds("9p"));
+console.log(formatPenceToPounds("39p"));
+console.log(formatPenceToPounds("399"));