London | May 2025 | Victoria Scott | Sprint 2 Coursework

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

@@ -4,3 +4,5 @@ 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 updates the value of the variable count by increasing it by 1. The expression on the right side of the = adds 1 to the current value of count, and the result is then stored back into count. The = symbol is an assignment operator. It takes the value on the right-hand side and assigns it to the variable on the left-hand side. In this case, it means take the result of count + 1 and assign it to count. = does not mean equality, like in mathematics; it means assignment in programming.

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

@@ -5,7 +5,7 @@ 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[0] + middleName[0] + lastName[0];
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 

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

@@ -17,7 +17,7 @@ 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(".") + 1);
 
 // https://www.google.com/search?q=slice+mdn

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
+
+// The variable num stores a random whole number between 1 and 100. The code uses Math.random() to get a number between 0 and 1. It then multiplies that number to get a value between 0 and 100. Math.floor() rounds it down to a whole number. Finally, it adds 1 so the result is between 1 and 100. Each time you run the code, num will be a different number in that range.

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?
+We don't want the computer to run these 2 lines - how can we solve this problem?
+
+// To stop the computer from running those two lines, we can turn them into comments by adding // at the beginning of each line. This tells the computer to ignore the line because it is only meant for humans to read.

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

@@ -2,3 +2,8 @@
 
 const age = 33;
 age = age + 1;
+
+// The code does not work because const creates a variable that cannot be changed. Since we want to increase the value of age, we should use let instead of const. This allows us to reassign the value of the variable:
+
+let age = 33;
+age = age + 1;

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

@@ -3,3 +3,7 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// You need to declare the variable before you use it. Code should look like this:
+const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -7,3 +7,12 @@ const last4Digits = cardNumber.slice(-4);
 // 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 this code will not work because cardNumber is a number, not a string, and .slice() is a method that only works on strings or arrays. Since numbers don’t have a .slice() method, it will likely throw a TypeError.
+// Ran the code, error message: TypeError: cardNumber.slice is not a function
+// As predicted. .slice doesn't work on numbers. .slice() is a string method, and cardNumber is a number. 
+// Corrected code:
+const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);
+

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

@@ -1,2 +1,7 @@
 const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const 24hourClockTime = "08:53";
+
+// There is an error in the variable name 12HourClockTime because JavaScript does not allow variable names to start with a number. 
+// Corrected code:
+const twelveHourClockTime = "20:53";
+const twentyFourHourClockTime = "08:53";

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

@@ -12,11 +12,39 @@ 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 is a total of 5 function calls:
+
+carPrice.replaceAll(",", "")
+Number(...)
+priceAfterOneYear.replaceAll("," "") 
+Number(...) 
+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?
+// This line has a syntax error:
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// The problem is that there’s a missing comma between ("," and "")
+// /By adding a comma the code is correct:
+priceAfterOneYear = Number(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?
+
+//carPrice.replaceAll(",", "") removes all the commas from the string turning it into 10000. Number(...) converts that string into a number so that you can do math with it.
+

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

@@ -12,14 +12,20 @@ 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?
+// 6
 
 // b) How many function calls are there?
+// 1
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// Remainder operator. It gives the number of seconds left after converting to full minutes.
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// Line 4 takes the total seconds in the movie, removes the leftover seconds, and divides by 60 to get the total number of full minutes.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// result represents the movie length written as hours:minutes:seconds. formattedMovieLength could be 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
+// It works for most normal, positive whole numbers, but may not work well with negative or non-integer values.

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

@@ -25,3 +25,11 @@ 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 removes the last character ("p") from the string. penceString.length - 1 gives the position of the last character. substring(0, ...) gets everything from the start up to (but not including) the "p".
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"); : Makes sure the string has at least 3 characters by adding zeros at the beginning if necessary. This is to ensure there is always enough digits to split into pounds and pence.
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2); : Takes all but the last two digits to get the pounds part of the price.e.g. "399" = "3".
+// 5. const pence = paddedPenceNumberString : substring(paddedPenceNumberString.length - 2) / padEnd(2, "0"); - This gets the last two digits — the pence part — and makes sure it’s always 2 digits e.g. "399" = "99".
+// 6. console.log(`£${pounds}.${pence}`); : This puts everything together into pounds and pence format.
+
+
+

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

@@ -11,8 +11,9 @@ In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
 
 What effect does calling the `alert` function have?
+// Calling the alert function causes a popup message box to appear in the browser window. This box displays the message "Hello world!", and the user must click “OK” to close it.
 
 Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`.
 
-What effect does calling the `prompt` function have?
-What is the return value of `prompt`?
+What effect does calling the `prompt` function have? Calling the prompt function shows a popup asking "What is your name?" and a text input field asking the user to enter text, and click "ok" or "cancel". 
+What is the return value of `prompt`? The return value of prompt is the text the user types, as a string, or null if they click "Cancel". The result can be stored in a variable, myName, to be used later in the program.

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

@@ -5,12 +5,18 @@ In this activity, we'll explore some additional concepts that you'll encounter i
 Open the Chrome devtools Console, type in `console.log` and then hit enter
 
 What output do you get?
+ƒ log() { [native code] }
 
 Now enter just `console` in the Console, what output do you get back?
+console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, ...}
 
 Try also entering `typeof console`
 
 Answer the following questions:
 
 What does `console` store?
-What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+console stores a collection of functions (methods) used for displaying messages and debugging.
+What does the syntax `console.log` or `console.assert` mean? In particular, 
+
+what does the `.` mean? console is the object.
+.log or .assert refers to a a function stored inside that object.The '.' is used to access a specific function (or property) inside the console object.

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

@@ -1,5 +1,5 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  The code will throw a SyntaxError when defining the variable `str` inside the function.
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
@@ -9,5 +9,10 @@ function capitalise(str) {
   return str;
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+// =============> The error occurs because the function parameter is named str and inside the function the code tries to declare a new variable using let str = . In JavaScript, you are not allowed to declare a new variable with the same name as an existing parameter using let, const or var. This causes a SyntaxError that says the identifier str has already been declared. To fix the error, use a different variable name inside the function.
+// =============>
+
+  function capitalise(str) {
+  let capitalisedStr = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return capitalisedStr;
+}

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

@@ -1,7 +1,7 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// =============> An error will occur because the variable `decimalNumber` is being declared twice. Once as a function parameter and again using `const` inside the function.
 
 // Try playing computer with the example to work out what is going on
 
@@ -14,7 +14,13 @@ function convertToPercentage(decimalNumber) {
 
 console.log(decimalNumber);
 
-// =============> write your explanation here
+// =============> The error happens because the function `convertToPercentage` has a parameter named `decimalNumber`, and then inside the function body, it tries to declare a new constant also named `decimalNumber`. In JavaScript, you cannot declare a new variable with the same name as a parameter using `const`, `let` or `var`, because it causes a naming conflict. This results in a SyntaxError: "Identifier 'decimalNumber' has already been declared".
 
 // 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));

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

@@ -3,18 +3,23 @@
 
 // this function should square any number but instead we're going to get an error
 
-// =============> write your prediction of the error here
+// =============> The code will throw a SyntaxError because function parameters must be named variables, but here a number (3) is being used instead.
 
 function square(3) {
     return num * num;
 }
 
-// =============> write the error message here
+// =============> SyntaxError: Unexpected number
 
-// =============> explain this error message here
+// =============> In JavaScript, when you define a function you must use a variable name for the parameter, not a literal value like a number. In this code, `function square(3)` is invalid because `3` is a number, not a variable name. The interpreter expects a variable, so using a number causes a "SyntaxError: Unexpected number". Additionally, inside the function, the code uses a variable `num` that was never declared, which would also cause a ReferenceError if the function were defined properly.
 
 // Finally, correct the code to fix the problem
 
-// =============> write your new code here
+// =============> 
+function square(num) {
+  return num * num;
+}
+
+console.log(square(3));
 
 

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

@@ -1,14 +1,20 @@
 // Predict and explain first...
 
-// =============> write your prediction here
+// =============> The console will print the result of the multiplication (320), but the final output will also include `undefined` in the string, because the `multiply` function doesn't return a value.
+
 
 function multiply(a, b) {
   console.log(a * b);
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
-// =============> write your explanation here
+// =============> The function `multiply(a, b)` logs the result of `a * b` to the console, but it does not return anything. When you use the function call inside a template string, JavaScript expects a return value to insert into the string. Since `multiply(10, 32)` returns `undefined`, the final output will be: 320. The result of multiplying 10 and 32 is undefined. This happens because the function only logs the result but doesn’t return it.
 
 // 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

@@ -1,5 +1,5 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============> The code will run without crashing, but the output will say: "The sum of 10 and 32 is undefined"
 
 function sum(a, b) {
   return;
@@ -8,6 +8,12 @@ function sum(a, b) {
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
-// =============> write your explanation here
+// =============> In the `sum` function, the `return` statement is followed by a semicolon, which ends the function early before it reaches `a + b`. This means the function returns `undefined` instead of the actual sum. In JavaScript, if you put a line break right after `return`, JavaScript automatically ends the statement. As a result, `a + b` is never executed, and `undefined` is returned.
+
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+//  =============> 
+  function sum(a, b) {
+    return a + b;
+  }
+
+  console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);

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

@@ -1,7 +1,7 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// =============> All three console.log statements will say the last digit of the same number: 103. The function getLastDigit() does not use the number passed into it, so the output will always be based on the global variable `num`.
 
 const num = 103;
 
@@ -14,11 +14,22 @@ console.log(`The last digit of 105 is ${getLastDigit(105)}`);
 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 take any parameters. Instead, it always uses the variable `num`, which is set to 103. When the function is called with values like `getLastDigit(42)`, `42` is ignored because the function doesn't accept any parameters. As a result, it always converts 103 to a string and returns the last character — "3" — every time. This is why the output shows "3" as the last digit for all numbers, even though it's incorrect.
+
 // 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

@@ -15,5 +15,7 @@
 // It should return their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
+    const bmi = weight / (height * height);
+    return Number(bmi.toFixed(1));
+  }
     // return the BMI of someone based off their weight and height
-}

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

@@ -14,3 +14,9 @@
 // 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
+
+function toUpperSnakeCase(input) {
+    return input.replace(/ /g, "_").toUpperCase();
+  }
+
+  // This function takes a string as input and returns it in UPPER_SNAKE_CASE format. It does this by replacing all the spaces with underscores using .replace(/ /g, "_"), and then it converts the entire string to uppercase letters using .toUpperCase().

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

@@ -3,4 +3,24 @@
 // You will need to take this code and turn it into a reusable block of code.
 // 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
+// You should call this function a number of times to check it works for different input
+
+function toPounds(penceString) {
+    const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+
+    const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+    const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+
+    const pence = paddedPenceNumberString
+      .substring(paddedPenceNumberString.length - 2)
+      .padEnd(2, "0");
+
+    return `£${pounds}.${pence}`;
+  }
+
+console.log(toPounds("399p"));   // £3.99
+console.log(toPounds("99p"));    // £0.99
+console.log(toPounds("5p"));     // £0.05
+console.log(toPounds("12345p")); // £123.45
+console.log(toPounds("0p"));     // £0.00