London | 26-ITP-January | Eugenie Ahangama | Sprint 1 | coursework/sprint-1

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

@@ -1,6 +1,7 @@
 let count = 0;
 
-count = count + 1;
+count = count + 1;  // increment: adds 1 and assigns the new value back
 
-// 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
+// MDN Increment operator: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Increment
+// MDN Assignment operators: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators#Assignment_operators
+// Alternatives: count += 1 or 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 = ``;
-
-// https://www.google.com/search?q=get+first+character+of+string+mdn
+// + joins them in one string
+// [0] gets the first character of each string
+let initials = firstName[0] + middleName[0] +lastName[0]; 
+console.log(initials); // "CKJ"
 
+// 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

@@ -1,9 +1,28 @@
 const minimum = 1;
 const maximum = 100;
 
-const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum; // Generates a random whole number between minimum and maximum
 
 // 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
+
+// Generates a random decimal number in the interval [0, 1)
+// (includes 0, excludes 1)
+// MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random
+const decimal = Math.random();
+// Calculates the range size
+const range = maximum - minimum + 1;
+// Scales the decimal to the range
+const scaled = decimal * range;
+// Rounds down to get a whole number
+const floored = Math.floor(scaled);
+// Shifts the number up to start at the minimum
+const result = floored + minimum;
+// Logs each part to understand the process
+console.log("decimal:", decimal);
+console.log("range:", range);
+console.log("scaled:", scaled);
+console.log("floored:", floored);
+console.log("result:", result);

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 +1,6 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+// let allows reassignment whereas const does not
+let age = 33;
 age = age + 1;
+console.log(age);

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

@@ -3,3 +3,11 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// The error is that the variable cityOfBirth is used before it is declared and assigned a value.
+// To fix the error, we need to declare and assign a value to cityOfBirth before using it in the console.log statement.
+
+/* Corrected code:
+const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+*/

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

@@ -1,5 +1,11 @@
+// Prediction: The code will not work because cardNumber is defined as a number not a string. 
+// The slice method is a string and arrays method, and cannot be used on a number type.
+// Error: TypeError: cardNumber.slice is not a function
+
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().slice(-4);
+
+console.log(last4Digits); // Should output: 4213
 
 // 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 +1,8 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+// Prediction: The code will fail because variable names cannot start with a number.
+// JavaScript identifiers must begin with a letter, $, or _. Starting with a 12 or 24 is invalid.
+// The quotes used are also smart quotes which will cause a syntax error.
+
+// Corrected code:
+
+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;
@@ -12,11 +12,37 @@ 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
+// carPrice.replaceAll(",", "") - line 4
+// Number(...) - line 4, wraps the result of replaceAll
+// priceAfterOneYear.replaceAll("," "") - line 5
+// Number(...) - line 5, wraps the second result of replaceAll
+// console.log(..) - line 9
+// Answer: There are 5 function calls in total, on lines 4, 5 and 9.
 
 // 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?
+// Error: priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// Answer: 
+// The red line on replaceAll("," "") indicates that there is a syntax error on line 5, as shown in the code.
+// A comma was missing between the two arguments inside the replaceAll function call.
+// To fix this, add a comma between the two arguments like this: replaceAll(",", "").
+
+// Error: SyntaxError: missing ) after argument list and price AfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// The error appears on the console.log line because the string was written using smart quotes instead of normal JavaScript quotes.
+// Smart quotes break the strong syntax rules of JavaScript. 
+// To fix this, replace the smart quotes with straight quotes.
 
 // c) Identify all the lines that are variable reassignment statements
+// carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+// Answer: Lines 4 and 5 are variable reassignment statements.
 
 // 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;
+// Answer: Lines 1, 2, 7 and 8 are variable declarations.
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// The expression Number(carPrice.replaceAll(",", "")) is removing all the commas from carPrice string by replacing every comma with an empty string.
+// The purpose is to clean the value so that it can be converted to a proper number using Number().

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

@@ -12,14 +12,33 @@ 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?
+// movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours, result
+// Answer: Each uses const, so each counts as a declaration. There are 6 variable declarations in total.
 
 // b) How many function calls are there?
+// console.log(result)
+// Answer: There is 1 function call in this program. Everything else is arithmetic, not a function call.
 
 // 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 documentation, the remainder operator (%) returns the remainder after dividing one number by another.
+// In this case, movieLength % 60 divides movieLength (which is in seconds) by 60, 
+// returns the leftover seconds that don't fit into a full minute.
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// This line removes the leftover seconds (remainingSeconds) and converts the remaining whole seconds into minutes. 
+// So it gives you the total number of whole minutes in the movie.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// The result variable represents the final formatted time of the movie in hours, minutes and seconds.
+// hours:minutes:seconds format. A better name could be formattedTime or movieDuration.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// If I set movieLength to 8784, the output will be "2:26:24", which is correct, 
+// so this is a normal case where the code works as expected.
+
+// If I set movieLength to 0, the output will be "0:0:0", which is also correct, 
+// shows it can handle edge cases even though it is an unusual value.
+
+// If I set movieLength to -200, the output will be "-1:-3:-20", which is not a valid time format, 
+// shows that the logic breaks because the code does not protect against invalid negative inputs.

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

@@ -25,3 +25,28 @@ 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): 
+// Removes the final "p" character so only the numeric part of the price remains
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"): 
+// Ensures the number is atleast 3 digits long by adding leading zeros when necessary, which helps with consistent formatting
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2): 
+// Extracts everything except the last two digits to form the pounds portion of the price
+
+// 5. const pence = paddedPenceNumberString .substring(paddedPenceNumberString.length - 2) .padEnd(2, "0"):
+// Takes the final two digits of the padded string to form the pence portion
+
+// 6. console.log(`£${pounds}.${pence}`):
+// Combines the pounds and pence into a standard currency format and prints it to the console, "£3.99"
+
+// Test cases to consider:
+// "5p" should output "£0.05"
+// "99p" shsould output "£0.99"
+// "399p" should output "£3.99"
+// "0p" should output "£0.00"
+// "1000p" should output "£10.00"
+
+// The program takes a string representing a price in pence (e.g., "399p")
+// and converts it to a string representing the price in pounds (e.g., "£3.99").

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

@@ -11,8 +11,12 @@ In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
 
 What effect does calling the `alert` function have?
+- Shows a message in a pop up box and stops the page 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?
+- Shows a pop up box with a message and an input box.
+
 What is the return value of `prompt`?
+- Prompt() returns the text the user enters, or null if they cancel the dialog.

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

@@ -5,12 +5,20 @@ 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`
+- 'object'
 
 Answer the following questions:
 
 What does `console` store?
+- `console` is an object that contains methods for outputting messages to the browser console, such as `log()`, `error()`, `warn()`, `info()`, `debug()`, `assert()` and more.
+- It does **not** store the history of printed messages - the browser's console UI handles that history.
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+- You are accessing a function (a method) that belongs to the console object.
+- The `.` is used to access that method from the object.