Barcelona | Oct2025-2 | Roman Pavlenko | Sprint-1 | Coursework

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

@@ -4,3 +4,8 @@ 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
+// Line 3 is updating the value of the count variable by adding 1 to its current value. 
+// The = operator assigns the new value back to the count variable.
+
+console.log(count);
+// Expected output: 1

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

@@ -4,8 +4,17 @@ 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.
+const index = 0;
+let initials = firstName.charAt(index) +
+               middleName.charAt(index) +
+               lastName.charAt(index);
 
-let initials = ``;
+console.log(`The first letters of ${firstName}'s name are ${initials}`);
+// Expected output: "CKJ"
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 
+
+
+console.log(firstName[0] + middleName[0] + lastName[0]);
+// Expected output: "CKJ

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(base.lastIndexOf("."));
+
+console.log(`The ext part of ${filePath} is ${ext}`);
+console.log(`The dir part of ${filePath} is ${dir}`);
 
 // https://www.google.com/search?q=slice+mdn

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

@@ -7,3 +7,12 @@ const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 // 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
+
+console.log(num);
+
+// Explanation:
+// 1. Math.random() generates a random floating-point number between 0 (inclusive) and 1 (exclusive) [0, 1) .
+// 2. Multiplying this random number by (maximum - minimum + 1) scales it to a range of 0 (inclusive) to (maximum - minimum + 1) (exclusive).
+// 3. Math.floor() then rounds this scaled number down to the nearest whole number, resulting in an integer from 0 to (maximum - minimum).
+// 4. Finally, adding 'minimum' shifts this range up, resulting in a final value between 'minimum' and 'maximum' (both inclusive).
+// Therefore, 'num' represents a random integer between 1 and 100, inclusive.

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

@@ -1,2 +1,4 @@
-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?
+/*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? 
+- So we can make a multi-line comment or a single-line comment */
+

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

@@ -1,4 +1,6 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+console.log(age);
+// The code above works fine. It was an error because of using 'const' instead of 'let'

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

@@ -1,5 +1,6 @@
 // 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}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+// The error was an order error - declaration must come before usage

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

@@ -1,9 +1,22 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
-
+// const last4Digits = cardNumber.slice(-4);
 // 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
+
+
+
+// TypeError: cardNumber.slice is not a function 
+// The error occurs because cardNumber is a number, and the slice() method is not defined for numbers.
+// The slice() method is a string method, so to use it, we need to convert cardNumber to a string first.
+// To fix the error, we can use the toString() method to convert cardNumber to a string before calling slice().
+// Updated code:
+let last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);
+last4Digits = Number(last4Digits);
+typeof last4Digits;
+console.log(`Last four digits of cardNumber are ${last4Digits} and type of this variable is ${typeof last4Digits}`);
+

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

@@ -1,2 +1,8 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+
+// Variable declaration expected.ts(1134)
+// The error occurs because variable names cannot start with a number in JavaScript.
+// To fix the error, we can rename the variables to start with a letter or an underscore.
+const hourClockTime12 = "20:53";
+const hourClockTimeEight24 = "08:53";
+
+console.log(`12-hour clock time is ${hourClockTime12} and 24-hour clock time is ${hourClockTimeEight24}`);

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

@@ -1,9 +1,7 @@
 let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
-
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
-
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
 
@@ -12,11 +10,28 @@ console.log(`The percentage change is ${percentageChange}`);
 // Read the code and then answer the questions below
 
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
+// There are 4 function calls in this file. They are on the following lines:
+// Line 3: carPrice.replaceAll(",", "")
+// Line 3: Number(carPrice.replaceAll(",", ""))
+// Line 4: priceAfterOneYear.replaceAll(",", "")
+// Line 4: Number(priceAfterOneYear.replaceAll(",", ""))
 
 // 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 code had an error in replaceAll because it wasn't a comma between the quotation marks.
 // c) Identify all the lines that are variable reassignment statements
-
+// The variable reassignment statements are on the following lines:
+// Line 3: carPrice = Number(carPrice.replaceAll(",", ""));
+// Line 4: priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 // d) Identify all the lines that are variable declarations
+// The variable declaration statements are on the following lines:
+// Line 1: let carPrice = "10,000";
+// Line 2: let priceAfterOneYear = "8,543";
+// Line 5: const priceDifference = carPrice - priceAfterOneYear;
+// Line 6: const percentageChange = (priceDifference / carPrice) * 100;
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// The expression Number(carPrice.replaceAll(",","")) is performing two main tasks:
+// 1. carPrice.replaceAll(",","") - This part of the expression is using the replaceAll method to remove all commas from the string value of carPrice. 
+// This is necessary because commas are not valid in numerical representations and would cause issues when trying to convert the string to a number.
+// 2. Number(...) - The outer Number function takes the resulting string (which now has no commas) and converts it into a numerical value. This allows
+//  for mathematical operations to be performed on carPrice, such as subtraction and percentage calculations later in the code.

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

@@ -1,25 +1,58 @@
-const movieLength = 8784; // length of movie in seconds
+const movieLength = 86400 ; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
+console.log(remainingSeconds);
 const totalMinutes = (movieLength - remainingSeconds) / 60;
-
+console.log(totalMinutes);
 const remainingMinutes = totalMinutes % 60;
+console.log(remainingMinutes);
 const totalHours = (totalMinutes - remainingMinutes) / 60;
-
+console.log(totalHours);
 const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
 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 5 variable declarations in this program. They are on the following lines:
+// Line 1: const movieLength = 8784; // length of movie in seconds
+// Line 3: const remainingSeconds = movieLength % 60;
+// Line 5: const totalMinutes = (movieLength - remainingSeconds) / 60;
+// Line 7: const remainingMinutes = totalMinutes % 60;
+// Line 9: const totalHours = (totalMinutes - remainingMinutes) / 60;
+// Line 11: const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
 
 // b) How many function calls are there?
+// There is 1 function call in this program. It is on the following line:
+// Line 11: console.log(result);
+// Hint: Template literals are not function calls
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
+// The expression movieLength % 60 calculates the remainder when movieLength is divided by 60.
+// The % operator is known as the modulus operator, and it returns the remainder of a division operation.
+// In this case, it is used to determine how many seconds are left over after accounting for complete minutes in the total movie length.
+// For example, if movieLength is 8784 seconds, dividing by 60 gives 146 minutes with a remainder of 24 seconds.
+// Therefore, movieLength % 60 would evaluate to 24.
+
+// Documentation reference:
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
-
+// The expression assigned to totalMinutes is (movieLength - remainingSeconds) / 60.
+// This expression calculates the total number of complete minutes in the movie length by first subtracting the remaining seconds from the total movie length (in seconds) 
+// to get a value that is a multiple of 60 (i.e., the total seconds that can be evenly divided into minutes).
+// Then, it divides that result by 60 to convert the total seconds into minutes.
+// For example, if movieLength is 8784 seconds and remainingSeconds is 24 seconds, 
+// then (8784 - 24) equals 8760 seconds, which when divided by 60 gives 146 minutes.
+// Therefore, totalMinutes would evaluate to 146.
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// The variable result represents the formatted string of the movie length in hours, minutes, and seconds (HH:MM:SS).
+// A better name for this variable could be formattedMovieLength or movieDurationFormatted, as these names more clearly indicate that the variable holds a formatted representation of the movie length.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// This code will work for all non-negative integer values of movieLength, as it correctly calculates the hours, minutes, and seconds for any given length in seconds.
+// However, if movieLength is a negative value, the calculations may not make sense in the context of time duration, 
+// as negative time durations are not typically represented in hours, minutes, and seconds.
+// Additionally, if movieLength is not an integer (e.g., a floating-point number), the calculations may yield unexpected results due to the way division and modulus operations work with non-integer values.
+// Therefore, it is advisable to ensure that movieLength is a non-negative integer for the code to function as intended.
+// If movieLength is extremely large, the code will still work, but we should consider adding additional formatting to handle cases where the number of hours exceeds 24.

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

@@ -1,19 +1,22 @@
-const penceString = "399p";
+const penceString = "18399p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
   penceString.length - 1
 );
-
+console.log(penceStringWithoutTrailingP);
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
+console.log(pounds);
+
 
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
+console.log(pence);
 
 console.log(`£${pounds}.${pence}`);
 
@@ -25,3 +28,19 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 2. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+//    - This line removes the trailing 'p' from the pence string to isolate the numeric part
+//    - It uses the substring method to extract all characters from the start of the string up to (but not including) the last character
+// 3. console.log(penceStringWithoutTrailingP): logs the modified pence string without the trailing 'p' to the console for verification
+// 4. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//    - This line ensures that the numeric string has at least three characters by padding it with leading zeros if necessary
+//    - This is important for correctly separating pounds and pence later on
+// 5. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+//    - This line extracts the pounds part of the price by taking all characters except for the last two (which represent pence)
+// 6. console.log(pounds): logs the extracted pounds value to the console for verification
+// 7. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
+//    - This line extracts the pence part of the price by taking the last two characters of the padded string
+//    - It also ensures that there are always two digits for pence by padding with a trailing zero if necessary
+// 8. console.log(pence): logs the extracted pence value to the console for verification
+// 9. console.log(`£${pounds}.${pence}`);
+//    - Finally, this line constructs and logs the final price in pounds and pence format, prefixed with the pound symbol (£)

Sprint-1/4-stretch-explore/objects.md

@@ -13,4 +13,11 @@ Try also entering `typeof console`
 Answer the following questions:
 
 What does `console` store?
+console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …}
+it provides a set of methods (functions) we can call to interact with the debugging console.
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+log() { [native code] }
+assert() { [native code] }
+the log/assert methods inside console.
+. - property accessor (like saying “go inside this object and grab this property or method”).