London | May 2025 | Samuel Tarawally | Sprint 1 | Coursework

.gitignore

@@ -1,4 +1,6 @@
 node_modules
 .DS_Store
 .vscode
-**/.DS_Store
+**/.DS_Store
+**/runme.md
+.devcontainer/

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

@@ -4,3 +4,7 @@ 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 reassigns the 'count' variable.
+// It evaluates the right side first (0 + 1 = 1), and then assigns that result back to the 'count' variable.
+// The 'count' variable is often used to keep track of the number of iterations or occurrences in a loop or process.

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

@@ -2,10 +2,6 @@ let firstName = "Creola";
 let middleName = "Katherine";
 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 = ``;
-
-// https://www.google.com/search?q=get+first+character+of+string+mdn
+let initials = `${firstName[0]}${middleName[0]}${lastName[0]}`;
 
+console.log(initials);

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

@@ -14,10 +14,9 @@ const lastSlashIndex = filePath.lastIndexOf("/");
 const base = filePath.slice(lastSlashIndex + 1);
 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 = filePath.slice(0, lastSlashIndex);
+const ext = base.slice(base.lastIndexOf("."));
 
-const dir = ;
-const ext = ;
-
-// https://www.google.com/search?q=slice+mdn
+console.log(`The base is: ${base}`);
+console.log(`The directory is: ${dir}`);
+console.log(`The extension is: ${ext}`);

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

@@ -7,3 +7,5 @@ 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(`The random number is: ${num}`);

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

@@ -1,2 +1,2 @@
-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?

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

@@ -1,4 +1,8 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+// The `const` keyword cannot be reassigned to a different object or array. 
+// Variable references of this type are considered immutable.
+// The `let` keyword allows variables to be declared and reassigned.
+let age = 33;
 age = age + 1;
+console.log(age);

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}`);
+// Variables must be declared before they are used.
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -1,9 +1,10 @@
-const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+// The following code will throw an error when run
+// since the variable cardNumber is an integer.
+// The slice method is not available on integers.
+// const cardNumber = 4533787178994213;
+// 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
+// Converting the integer to a string first will fix the issue.
+const cardNumber = 4533787178994213;
+const last4Digits = String(cardNumber).slice(-4);
+console.log(last4Digits);

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

@@ -1,2 +1,8 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+// Variable names in JavaScript cannot start with a number.
+// This code throws a SyntaxError when run.
+// const 12HourClockTime = "20:53";
+// const 24hourClockTime = "08:53";
+
+// The variable names should be valid identifiers, e.g.
+const twelveHourClockTime = "20:53";
+const twentyFourHourClockTime = "08:53";

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

@@ -2,7 +2,7 @@ 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;
@@ -11,12 +11,31 @@ 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
-
-// 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?
-
-// c) Identify all the lines that are variable reassignment statements
-
-// d) Identify all the lines that are variable declarations
-
-// e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+//  a) How many function calls are there in this file? Write down all the lines where a function call is made.
+//      There are 5 function calls in this file:
+//          1. `carPrice.replaceAll(",", "")` on line 4.
+//          2. `Number(carPrice.replaceAll(",", ""))` on line 4.
+//          3. `priceAfterOneYear.replaceAll(",", "")` on line 5.
+//          4. `Number(priceAfterOneYear.replaceAll(",", ""))` on line 5.
+//          5. `console.log(...)` on line 10.
+
+//  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 is coming from the line: `priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));`
+//      The error occurs because there is a missing comma between the two arguments in the `replaceAll()` method: `(",", "")`. It should be `replaceAll(",", "")`.
+//      To fix this, add a comma between the empty string and the comma character within the `replaceAll` function call, e.g. `priceAfterOneYear.replaceAll(",", "")`.
+
+//  c) Identify all the lines that are variable reassignment statements.
+//      - carPrice = Number(carPrice.replaceAll(",", ""));
+//      - priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
+//  d) Identify all the lines that are variable declarations.
+//      - let carPrice = "10,000";
+//      - let priceAfterOneYear = "8,543";
+//      - const priceDifference = carPrice - priceAfterOneYear;
+//      - const percentageChange = (priceDifference / carPrice) * 100;
+
+//  e) Describe what the expression Number(carPrice.replaceAll(",", "")) is doing – what is the purpose of this expression?
+//      This expression is performing two main operations:
+//          1. `carPrice.replaceAll(",", "")`: This part of the expression is called on the `carPrice` string ("10,000"). The `replaceAll()` method is used to remove all occurrences of the comma (",") character from the string. After this operation, "10,000" becomes "10000".
+//          2. `Number(...)`: This part then takes the resulting string ("10000") and converts it into a numerical data type.
+//      The purpose of this entire expression is to convert the string representation of a price, which includes a comma for readability, into a pure numerical value that can be used for mathematical calculations (such as subtraction and division to find the difference and percentage change).

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

@@ -1,5 +1,4 @@
-const movieLength = 8784; // length of movie in seconds
-
+const movieLength = -8784.847389543985709847385
 const remainingSeconds = movieLength % 60;
 const totalMinutes = (movieLength - remainingSeconds) / 60;
 
@@ -11,15 +10,38 @@ 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?
-
-// b) How many function calls are there?
-
-// c) Using documentation, explain what the expression movieLength % 60 represents
-// 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?
+//  a) How many variable declarations are there in this program?
+//      There are 6 variable declarations in this program, these are: 
+//          1. `movieLength`
+//          2. `remainingSeconds`
+//          3. `totalMinutes`
+//          4. `remainingMinutes`
+//          5. `totalHours`
+//          6. `result`.
+
+//  b) How many function calls are there?
+//      There is 1 function call in this program: `console.log(result)`.
+
+//  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 (`%`). 
+//      Per Mozilla Developer documentation, the remainder (%) operator returns the division remainder, with its sign matching the dividend's.
+//      `movieLength % 60` determines the seconds remaining after converting movieLength to full minutes.
+
+//  d) Interpret line 4. What does the expression assigned to totalMinutes mean?
+//      Line 4: `const totalMinutes = (movieLength - remainingSeconds) / 60;`
+//      This expression calculates the total number of whole minutes within `movieLength`. 
+//      It first subtracts `remainingSeconds` (which are the seconds that do not make up a full minute) from the `movieLength`. 
+//      This leaves only the seconds that form complete minutes.
+//      This value is then divided by 60 to convert these seconds into a total count of minutes.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
-
-// f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+//    The variable `result` represents the `movieLength` converted and formatted into a string showing hours, minutes, and seconds, in the format `HH:MM:SS`.
+//    A better name for this variable could be `movieDuration`, as it more clearly indicates its purpose and possible data type.
+
+// 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 positive integer values of `movieLength`.
+//    If `movieLength` is 0, the result will be "0:0:0", which is correct.
+//    If `movieLength` is a negative number, the remainder operator will return a negative remainder (e.g., -8784 % 60 would be "-2:-26:-24").
+//    If `movieLength` is a floating-point number, the calculations involving the remainder operator and division lead to floating-point values for `remainingSeconds`.
+//    Therefore, while it handles positive integers and non-integers well, it will not produce meaningful results for negative `movieLength` values and may therefore be

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

@@ -17,11 +17,48 @@ const pence = paddedPenceNumberString
 
 console.log(`£${pounds}.${pence}`);
 
-// This program takes a string representing a price in pence
-// The program then builds up a string representing the price in pounds
+// This programme takes a string representing a price in pence
+// It then constructs a string representing the price in pounds
 
-// You need to do a step-by-step breakdown of each line in this program
-// Try and describe the purpose / rationale behind each step
+// You need to provide a step-by-step breakdown of each line in this programme
+// Describe the purpose and reasoning behind each step
 
-// To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// To begin, we start with:
+// 1. const penceString = "399p": Initialises a string variable with the value "399p".
+// This represents the initial price in pence that the programme will process.
+
+// 2. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+// This line removes the trailing 'p' from `penceString` by:
+//    - `penceString.length`: Obtains the total length of `penceString`, which is 4.
+//    - `penceString.length - 1`: Calculates the index of the last character, which is 'p'.
+//    - `penceString.substring(0, penceString.length - 1)`: Extracts the substring from the start of `penceString` up to, but not including, the last character.
+//    - The result is the removal of the 'p' character, leaving "399".
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// This line declares a constant variable named `paddedPenceNumberString`.
+//    - It applies the `padStart()` method to `penceStringWithoutTrailingP` ("399").
+//    - `padStart(3, "0")` checks if the string's length is less than 3. 
+//    - If so, it adds "0" to the beginning of the string until its length reaches 3.
+//    - In this case, "399" already has a length of 3, so it remains unchanged.
+//    - The purpose of this step is to ensure the pence value always has at least three digits (e.g., "5p" becomes "005", "99p" becomes "099").
+//    - This is important for consistently extracting the pounds and pence parts later, especially for values less than 100p.
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+// This line extracts the pounds part of the price.
+//    - It declares a constant variable named `pounds`.
+//    - It uses `substring(0, paddedPenceNumberString.length - 2)` on `paddedPenceNumberString` ("399").
+//    - This extracts the substring from the start of the string up to, but not including, the last two characters.
+//    - In this example, it extracts "3" from "399".
+
+// 5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
+// This line extracts and formats the pence part of the price.
+//    - It declares a constant variable named `pence`.
+//    - It uses `substring(paddedPenceNumberString.length - 2)` on `paddedPenceNumberString` ("399").
+//    - This extracts the last two characters of the string, which are "99".
+//    - The `padEnd(2, "0")` method ensures the extracted pence value has at least two digits.
+
+// 6. console.log(`£${pounds}.${pence}`);
+// This final line constructs and prints the formatted price string to the console.
+//    - It uses a template literal to format the output as "£{pounds}.{pence}".
+//    - In this case, it outputs "£3.99", which is the price in pounds and pence format.
+//    - The `console.log` function displays the final result in the console.