London | ITP-May-2025 | Halyna Kozlovska | Module-Structuring-and-Testing-Data | Sprint-1

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

@@ -3,4 +3,4 @@ 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 statement that increases count by 1. The = operator reassigns the result of count + 1 back to the count variable.

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 = `${firstName.charAt(0)}${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

@@ -17,7 +17,11 @@ 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);
+console.log(`The dir part of ${filePath} is ${dir}`);
 
-// https://www.google.com/search?q=slice+mdn
+const lastDotIndex = base.lastIndexOf(".");
+const ext = base.slice(lastDotIndex);
+console.log(`The ext part of ${base} is ${ext}`);
+
+// https://www.google.com/search?q=slice+mdn

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

@@ -1,9 +1,18 @@
 const minimum = 1;
 const maximum = 100;
 
+// 1. Math.random() generates a decimal between 0 (inclusive) and 1 (exclusive)
+// 2. Multiply by (maximum - minimum + 1) to scale to the desired range size
+// 3. Math.floor() rounds down to get an integer from 0 up to range size minus 1
+// 4. Adding minimum shifts the range so the lowest number is minimum, not zero
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 
+// Result: num is a random integer between minimum and maximum, inclusive
+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
+
+

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

@@ -1,2 +1,6 @@
-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?
+
+// Explanation:
+// These lines are instructions, not JavaScript code
+// Added // to ignore them and prevent SyntaxError when running the file

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

@@ -1,4 +1,7 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+// use 'let' instead of 'const' for variables that need to be reassigned
+let age = 33;
 age = age + 1;
+// log the updated age value
+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}`);
+// declare cityOfBirth before using it to avoid ReferenceError
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -1,5 +1,8 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+// convert number to string before using slice
+const last4Digits = cardNumber.toString().slice(-4);
+// log the last 4 digits
+console.log(last4Digits);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working

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

@@ -1,2 +1,7 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+// Rename variables to valid identifiers because names cannot start with a number
+const ClockTime_12Hour = "08:53";
+const ClockTime_24Hour = "20:53";
+
+// Output the values
+console.log("Clock time in 12h format:", ClockTime_12Hour);
+console.log("Clock time in 24h format:", ClockTime_24Hour);

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 +13,35 @@ 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 in this file: 5
+// 1. carPrice.replaceAll(",", "") [line 4]
+// 2. Number(carPrice.replaceAll(",", "")) [line 4]
+// 3. priceAfterOneYear.replaceAll(",", "") [line 5]
+// 4. Number(priceAfterOneYear.replaceAll(",", "")) [line 5]
+// 5. console.log(`The percentage change is ${percentageChange}`); [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?
 
+// add missing comma between the two arguments inside replaceAll
+// priceAfterOneYear.replaceAll(",","") [line 5]
+
 // c) Identify all the lines that are variable reassignment statements
 
+// Variable reassignment statements: 2
+// 1. carPrice = Number(carPrice.replaceAll(",", "")); [line 4]
+// 2. priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",","")); [line 5]
+
+
 // d) Identify all the lines that are variable declarations
 
+// Variable declarations: 4
+// 1. let carPrice = "10,000"; [line 1]
+// 2. let priceAfterOneYear = "8,543"; [line 2]
+// 3. const priceDifference = carPrice - priceAfterOneYear; [line 7]
+// 4. const percentageChange = (priceDifference / carPrice) * 100; [line 8]
+
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+// Firstly, carPrice.replaceAll(",", "") removes all commas from the string
+// Then Number(...) converts the resulting string into a number type so it can be used in arithmetic

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

@@ -6,20 +6,47 @@ const totalMinutes = (movieLength - remainingSeconds) / 60;
 const remainingMinutes = totalMinutes % 60;
 const totalHours = (totalMinutes - remainingMinutes) / 60;
 
-const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
-console.log(result);
+// Rename result to formattedTime for clarity
+const formattedTime = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
+console.log(formattedTime);
 
 // 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 6 variable declarations:
+// movieLength, [line 1]
+// remainingSeconds, [line 3]
+// totalMinutes, [line 4]
+// remainingMinutes, [line 6]
+// totalHours, [line 7]
+// result. [line 9]
+
 // b) How many function calls are there?
 
+// There is 1 function call:
+// console.log() [line 9]
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
+// The % operator is the remainder operator.
+// movieLength % 60 gives the remainder after dividing movieLength by 60,
+// which represents the leftover seconds after counting full minutes.
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+// totalMinutes calculates how many whole minutes are in movieLength by
+// subtracting leftover seconds and dividing the remainder by 60.
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+// Result is the movie length formatted as "hours:minutes:seconds".
+// A better name could be formattedTime.
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// 1. The code correctly converts movieLength into hours, minutes, and seconds for positive values.
+// 2. It doesn’t handle zero or negative values properly—these cases need extra checks.
+// 3. Minutes and seconds may appear without leading zeros.
+// 4. To improve add validation to handle zero or negative inputs gracefully.

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

@@ -1,20 +1,26 @@
+// 1. Initialise a string representing a price in pence with a trailing "p"
 const penceString = "399p";
 
+// 2. Remove the trailing "p" from the string to isolate the numeric part
 const penceStringWithoutTrailingP = penceString.substring(
   0,
   penceString.length - 1
 );
 
+// 3. Pad the numeric string with leading zeros to ensure it has at least 3 digits
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// 4. Extract the pounds part by taking all but the last two digits
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
 
+// 5. Extract the pence part by taking the last two digits and pad with trailing zero if needed
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
 
+// 6. Output the formatted price in pounds and pence
 console.log(`£${pounds}.${pence}`);
 
 // This program takes a string representing a price in pence

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

@@ -9,10 +9,14 @@ Let's try an example.
 
 In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
+- Display a popup message with the text "Hello world!".
 
 What effect does calling the `alert` function have?
+- Pauses the script until the user clicks OK.
 
 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?
+- Calling the `prompt` function displays a dialog box with a message and an input field where the user can type a response.
 What is the return value of `prompt`?
+- Value of `prompt` returns the string entered by the user, or null if the user cancels the input.

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

@@ -3,14 +3,18 @@
 In this activity, we'll explore some additional concepts that you'll encounter in more depth later on in the course.
 
 Open the Chrome devtools Console, type in `console.log` and then hit enter
-
 What output do you get?
+- The function definition of log. Example: ƒ log() { [native code] }
 
 Now enter just `console` in the Console, what output do you get back?
+- The whole console object with many functions inside. Example: console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …}
 
 Try also entering `typeof console`
+- "object" because console is an object.
 
 Answer the following questions:
 
 What does `console` store?
+- It stores tools to show messages in the browser’s console.
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+- The `.` means “use this function from the console object.” For example, console.log means “use the log function from console.”