London | 25-ITP-September | Carlos Abreu | Sprint 2 | Coursework

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

@@ -4,3 +4,10 @@ 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 increase the count variable by 1 then assign the result in right hand side to count variable
+ */
+
+console.log('Value of count variable: ', 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 = ``;
+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

@@ -15,9 +15,14 @@ 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
+const dir = filePath.slice(0, lastSlashIndex);
+
 // Create a variable to store the ext part of the variable
+const lastDotIndex = filePath.lastIndexOf(".");
+const ext = filePath.slice(lastDotIndex);
+
+console.log(`The dir part of ${filePath} is ${dir}`);
+console.log(`The ext part of ${filePath} is ${ext}`);
 
-const dir = ;
-const ext = ;
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn

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

@@ -3,7 +3,47 @@ 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
+
+/**
+ * Step 1: Math.random()
+
+ * This generates a random decimal number between 0 (inclusive) and 1 (exclusive).
+ * Example: 0.3728, 0.9134, etc.
+
+ * Step 2: (maximum - minimum + 1)
+
+ * This calculates the range of possible numbers you want.
+ * Here: 100 - 1 + 1 = 100
+ * So, we’re creating a range that includes both 1 and 100.
+
+ * Step 3: Math.random() * (maximum - minimum + 1)
+
+ * This scales the random decimal to the range.
+ * Example: If Math.random() returns 0.3728,
+ * 0.3728 * 100 = 37.28
+
+ * Step 4: Math.floor(...)
+
+ * Math.floor() rounds down to the nearest whole number.
+ * So 37.28 becomes 37.
+
+ * Step 5: + minimum
+
+ * Because the range started from 0, we add minimum (which is 1) to shift it to the correct range.
+
+ * Example: 37 + 1 = 38.
+
+ * So what does num represent?
+ * num is a random integer between 1 and 100 (inclusive).
+ * Every time you run the program, you’ll get a different number in that range.
+
+ * Running it several times — you’ll see numbers like 27, 99, 7, 100, etc.
+
+*/
+

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

@@ -1,2 +1,29 @@
-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?
+
+/** If you have lines that are just instructions or notes for humans and you don’t want the computer to execute them, you can turn them into comments.
+
+In JavaScript, there are two ways to write comments:
+
+1. Single-line comment
+
+Use // at the start of a line.
+Everything after // is ignored by the computer.
+
+Example:
+
+// This line explains what the code does
+const num = 8;
+
+2. Multi-line comment
+
+Use \ /* ... *\ / to wrap several lines.
+
+Example:
+This section is just instructions
+The computer will ignore everything between these symbols
+
+const num = 5;
+
+*/
+

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;
+// change keyword 'const' to 'let'
+let age = 33;
 age = age + 1;
+
+console.log(age);
+

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

@@ -1,5 +1,9 @@
 // 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}`);
+// this is a very common JavaScript error related to variable hoisting and the temporal dead zone.
+// Simply declare the variable before you use it
+
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+

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

@@ -1,9 +1,34 @@
-const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+// 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
+
+/** 
+ *Prediction: Why won’t this code work?
+const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.slice(-4);
+
+
+The issue is that .slice() is a string method, but cardNumber here is a number — not a string.
+So when the code runs, JavaScript will say something like:
+
+TypeError: cardNumber.slice is not a function
+
+That’s because .slice() only works on strings or arrays — and numbers don’t have that method.
+
+Fixing the problem
+
+To use .slice(), we need to convert the number into a string first:
+
+Now it works!
+*/
+
+const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits); // "4213"
+

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

@@ -1,2 +1,18 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+// const 12HourClockTime = "20:53";
+// const 24hourClockTime = "08:53";
+
+/**
+ * In javascript variable can't start with a number
+ * Can contain letters, digits (but not at the start), underscore _, and dollar signs $
+ *
+ * const 12HourClockTime = "20:53"; will cause a SyntaxError because variable names can't begin with a number. 
+ *
+ * To fix it by changing the name to start with a letter.
+ */
+
+const twelveHourClockTime = "08:53";
+const twentyFourClockTime = "20:53";
+
+console.log(twelveHourClockTime);
+console.log(twentyFourClockTime);
+

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;
@@ -13,10 +13,40 @@ 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
 
+// Function calls and their line numbers
+// line 3 - carPrice.replaceAll(",", "") - Callls replaceAll() on the string to remove commas
+// line 3 - Number(...) - Converts the resulting string to a number
+// line 4 - priceAfterOneYear.replaceAll("," "") - Syntax error here - Intendend to replaceAll() but missing a comma between arguments
+// line 8 - console.log(...) - Prints to console 
+// // Total intended function calls: 5
+
 // 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?
 
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// Error: SyntaxError: missiong ) after argument list
+// Reason:
+// There's a missing comma between the arguments of replaceAll.
+// The correct syntax should be:
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
 // c) Identify all the lines that are variable reassignment statements
 
+// These are the lines where variables that were already declared are assigned a new value:
+// carPrice = Number(carPrice.replaceAll(",", "");
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+// Reassignments: Lines 3 and 4
+
 // d) Identify all the lines that are variable declarations
 
+// These are the lines where variables are first introduced:
+// 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 commas from the string "10,000", then it becomes "10000"
+// Number("10000") - Converts the string "10000" into a numeric value 10000.
+// Purpose: To convert a formatted currency string (with commas) into a number that can be used for mathematical calculations.
+

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

@@ -12,14 +12,79 @@ 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?
+// Each const introduces a new variable.
+// 
+// movieLength
+// remainingSeconds
+// totalMinutes
+// remainingMinutes
+// totalHours
+// result
+// Total variable declarations: 6
 
 // b) How many function calls are there?
 
+// The only function call is:
+
+// Total function calls: 1
+// 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
 
+// According to the MDN documentation on the remainder (%) operator
+// The remainder operator returns the remainder left over when one operand is divided by a second operand.
+// So:
+// movieLength % 60
+// means “the remainder when movieLength is divided by 60.”
+// Interpretation:
+// It gives you the remaining seconds that don’t make up a full minute.
+// For example, if the movie length were 125 seconds:
+// 125 % 60 = 5, so there are 5 seconds left over after 2 full minutes.
+// Purpose: Extract the leftover seconds after converting total seconds into minutes.
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+// const totalMinutes = (movieLength - remainingSeconds) / 60;
+// This line:
+// Subtracts the leftover seconds (that couldn’t form a full minute).
+
+// Divides the remaining seconds by 60.
+// Meaning:
+// Converts the total movie length into minutes, ignoring any incomplete minute.
+// So it gives the total number of full minutes in the movie.
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+// const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
+
+// This combines hours, minutes, and seconds into a single string formatted like H:M:S.
+// Example output: "2:26:24"
+// Meaning: It represents the formatted time duration of the movie.
+// Better variable names:
+// formattedDuration
+// timeString
+// movieTime
+// durationInHMS
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// It will work correctly for most positive integers, since it’s just converting seconds into hours, minutes, and seconds using division and remainders.
+// However, there are some edge cases:
+// If movieLength = 0:
+// Output: 0:0:0 ✅ Works fine.
+// If movieLength < 60 (less than a minute):
+// Works fine (e.g., 45 → 0:0:45).
+// If movieLength is not an integer (e.g., 87.5):
+// Still works, but decimals might appear in remainingSeconds.
+// If movieLength is negative:
+// The logic breaks — you’d get negative time components ❌.
+// Formatting issue:
+
+// The output isn’t padded.
+// Example: 2 hours, 5 minutes, 9 seconds → "2:5:9" instead of "02:05:09".
+// (Can fix that with .padStart(2, '0') on each component.)
+
+// Summary:
+// It works for positive whole numbers, but for negative or non-integer inputs, or if you need formatted time, adjustments are needed.
+