Birmingham | 26-ITP-May | Gabriel Pawuoi| Sprint 2 | Coursework

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

@@ -3,4 +3,5 @@ let count = 0;
 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 a variable reassignment. The = (assignment operator) takes the result of count + 1
+// (which evaluates to 1) and stores it back into the existing count variable, replacing the old value.

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("."));
 
 // https://www.google.com/search?q=slice+mdn

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

@@ -3,7 +3,15 @@ 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
+// num represents a random integer between 1 and 100 (inclusive).
+//
+// Breakdown:
+// 1. Math.random() generates a random decimal in [0, 1)
+// 2. (maximum - minimum + 1) = 100, so Math.random() * 100 gives a decimal in [0, 100)
+// 3. Math.floor(...) rounds down to an integer in [0, 99]
+// 4. Adding minimum (1) shifts the range to [1, 100]
+//
+// So num is a random whole number from 1 to 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?
+// 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?
+// Solution: Prefix each line with // to make them comments, as done here.

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

@@ -1,4 +1,6 @@
 // trying to create an age variable and then reassign the value by 1
+// Error: Assignment to constant variable.
+// const variables cannot be reassigned. Fix: use let instead.
 
-const age = 33;
+let age = 33;
 age = age + 1;

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 ?
+// Error: ReferenceError - cityOfBirth is used before it is declared.
+// const is not hoisted like var. Fix: declare the variable before using it.
 
-console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -1,9 +1,9 @@
+// Prediction: .slice() is a string method, not a number method, so it will throw a TypeError.
+// Error: TypeError: cardNumber.slice is not a function
+// Fix: convert the number to a string first.
+
 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

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

@@ -1,2 +1,7 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+// Error: variable names cannot start with a digit.
+// Fix: rename the variables to valid identifiers.
+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";
+
+console.log(twentyFourHourClockTime);
+console.log(twelveHourClockTime);

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

@@ -2,21 +2,25 @@ 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;
 
 console.log(`The percentage change is ${percentageChange}`);
 
-// Read the code and then answer the questions below
+// a) Function calls:
+//    Line 4: replaceAll(",", "") and Number(...)
+//    Line 5: replaceAll(",", "") and Number(...)
+//    Line 10: console.log(...)
 
-// a) How many function calls are there in this file? Write down all the lines where a function call is made
+// b) The error on line 5 is a missing comma between the two arguments to replaceAll:
+//    replaceAll("," "") should be replaceAll(",", ""). Fixed above.
 
-// 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) Variable reassignment statements: lines 4 and 5 (carPrice = ..., priceAfterOneYear = ...)
 
-// c) Identify all the lines that are variable reassignment statements
+// d) Variable declarations: lines 1, 2 (let), lines 7, 8 (const)
 
-// 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?
+// e) Number(carPrice.replaceAll(",","")) first removes all commas from the string "10,000"
+//    turning it into "10000", then converts that string into the number 10000.
+//    This is necessary because you cannot do arithmetic on strings.

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

@@ -9,17 +9,22 @@ const totalHours = (totalMinutes - remainingMinutes) / 60;
 const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
 console.log(result);
 
-// For the piece of code above, read the code and then answer the following questions
+// a) There are 6 variable declarations: movieLength, remainingSeconds, totalMinutes,
+//    remainingMinutes, totalHours, result.
 
-// a) How many variable declarations are there in this program?
+// b) There is 1 function call: console.log(result) on line 10.
 
-// b) How many function calls are there?
+// c) movieLength % 60 uses the modulo (remainder) operator.
+//    It gives the remainder after dividing movieLength by 60, i.e. the leftover seconds
+//    that don't make a full minute.
 
-// c) Using documentation, explain what the expression movieLength % 60 represents
-// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// d) totalMinutes = (movieLength - remainingSeconds) / 60
+//    First, the remaining seconds are subtracted so the value is an exact multiple of 60.
+//    Dividing by 60 then converts the total seconds into whole minutes.
 
-// d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// e) result represents the movie length formatted as HH:MM:SS (hours:minutes:seconds).
+//    A clearer name would be formattedDuration or timeDisplay.
 
-// 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
+// f) The code works for any non-negative integer value of movieLength.
+//    It will not work correctly for negative values (a negative duration makes no sense)
+//    but for any valid seconds value >= 0 the arithmetic is correct.

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

@@ -17,11 +17,15 @@ 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
-
-// You need to do a step-by-step breakdown of each line in this program
-// Try and describe the purpose / rationale behind each step
-
-// To begin, we can start with
+// Step-by-step breakdown:
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 2. penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1)
+//    Removes the trailing "p", leaving "399"
+// 3. paddedPenceNumberString = "399".padStart(3, "0")
+//    Ensures the string is at least 3 characters long by padding with "0" on the left.
+//    "399" is already 3 chars so it stays "399". For "9p" this would give "009".
+// 4. pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2)
+//    Takes all characters except the last 2. For "399" this gives "3" (the pounds part).
+// 5. pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0")
+//    Takes the last 2 characters ("99") as the pence part, and pads to 2 chars if needed.
+// 6. console.log(`£${pounds}.${pence}`): prints "£3.99"

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

@@ -1,13 +1,23 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// Prediction: SyntaxError because `str` is re-declared with `let` inside the function
+// where it already exists as a parameter. You cannot use `let` to re-declare a variable
+// that already exists in the same scope.
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
+// Original broken code:
+// function capitalise(str) {
+//   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+//   return str;
+// }
+
+// Explanation: The parameter `str` already exists in the function scope.
+// Using `let str` tries to re-declare it, which is a SyntaxError.
+// Instead of reassigning `str` (which represents the original input),
+// we use a new const `capitalisedStr` to make it clear this is a different value.
+
 function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
+  const capitalisedStr = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return capitalisedStr;
 }
-
-// =============> write your explanation here
-// =============> write your new code here

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

@@ -1,20 +1,28 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// Prediction: Two errors — (1) re-declaring decimalNumber with const inside the function
+// when it is already a parameter causes a SyntaxError.
+// (2) console.log(decimalNumber) outside the function will throw ReferenceError because
+// decimalNumber is not defined in the outer scope.
 
 // Try playing computer with the example to work out what is going on
 
+// Original broken code:
+// function convertToPercentage(decimalNumber) {
+//   const decimalNumber = 0.5;
+//   const percentage = `${decimalNumber * 100}%`;
+//   return percentage;
+// }
+// console.log(decimalNumber);
+
+// Explanation: The parameter decimalNumber already exists in the function scope;
+// const re-declaration is illegal. Also, decimalNumber is not accessible outside the function.
+// Fix: remove the const re-declaration inside the function, and pass a value when calling it.
+
 function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
-
   return percentage;
 }
 
-console.log(decimalNumber);
-
-// =============> write your explanation here
-
-// Finally, correct the code to fix the problem
-// =============> write your new code here
+console.log(convertToPercentage(0.5));

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

@@ -1,20 +1,19 @@
-
 // Predict and explain first BEFORE you run any code...
 
 // 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;
-}
-
-// =============> write the error message here
+// Prediction: SyntaxError — a function parameter must be a valid identifier, not a number literal.
 
-// =============> explain this error message here
-
-// Finally, correct the code to fix the problem
-
-// =============> write your new code here
+// Original broken code:
+// function square(3) {
+//     return num * num;
+// }
 
+// Error message: SyntaxError: Unexpected number
+// Explanation: `3` is a number literal and cannot be used as a parameter name.
+// Parameters must be valid identifiers (variable names).
+// Fix: use a named parameter like `num`.
 
+function square(num) {
+  return num * num;
+}

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

@@ -1,14 +1,19 @@
 // Predict and explain first...
+// Prediction: The template literal will print "undefined" for the function result because
+// multiply uses console.log internally but does not return a value (returns undefined).
 
-// =============> write your prediction here
+// Original broken code:
+// function multiply(a, b) {
+//   console.log(a * b);
+// }
+// console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
+
+// Explanation: Functions without a return statement return undefined.
+// The outer console.log then interpolates undefined into the string.
+// Fix: replace console.log inside multiply with a return statement.
 
 function multiply(a, b) {
-  console.log(a * b);
+  return a * b;
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
-
-// =============> write your explanation here
-
-// Finally, correct the code to fix the problem
-//  =============> write your new code here

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

@@ -1,13 +1,20 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// Prediction: The sum will print "undefined" because return; exits the function
+// immediately without a value, so a + b is never evaluated.
+
+// Original broken code:
+// function sum(a, b) {
+//   return;
+//   a + b;
+// }
+// console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+
+// Explanation: return; with no expression returns undefined.
+// The a + b on the next line is unreachable dead code and is never executed.
+// Fix: put a + b on the same line as return.
 
 function sum(a, b) {
-  return;
-  a + b;
+  return a + b;
 }
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
-
-// =============> write your explanation here
-// Finally, correct the code to fix the problem
-//  =============> write your new code here

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

@@ -1,24 +1,29 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// Prediction: All three logs will print "3" (the last digit of the module-level const num = 103)
+// because getLastDigit ignores its parameter and always uses the outer num.
+// Expected output:
+//   The last digit of 42 is 3
+//   The last digit of 105 is 3
+//   The last digit of 806 is 3
 
-const num = 103;
+// Original broken code:
+// const num = 103;
+// function getLastDigit() {
+//   return num.toString().slice(-1);
+// }
 
-function getLastDigit() {
+// Actual output matched prediction — all printed "3".
+
+// Explanation: The function has no parameter, so any argument passed in is discarded.
+// It always reads the outer `num` variable which is 103.
+// Fix: add a parameter to getLastDigit and use it instead of the outer variable.
+
+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)}`);
-
-// Now run the code and compare the output to your prediction
-// =============> write the output here
-// Explain why the output is the way it is
-// =============> write your explanation here
-// Finally, correct the code to fix the problem
-// =============> write your new code here
-
-// 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 +15,5 @@
 // It should return their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
-    // return the BMI of someone based off their weight and height
+  return Number((weight / (height * height)).toFixed(1));
 }