Cape Town | 26-ITP-Sep | Thabisile Malindi | Sprint 2 | Coursework: Sprint 2

Sprint-2/1-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 takes the current value of count, adds 1 to it, and assigns the new value back to count.
+//The = sign is the assignment operator. It assigns the value on the right side to the variable on the left side.

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

@@ -5,6 +5,6 @@ const 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.
 
-const initials = ``;
+const initials = `${firstName[0]}${middleName[0]}${lastName[0]}`;
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn

Sprint-2/1-key-exercises/3-paths.js

@@ -17,7 +17,8 @@ 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 lastDotIndex = filePath.lastIndexOf(".");
+const ext = filePath.slice(lastDotIndex);
 
 // https://www.google.com/search?q=slice+mdn

Sprint-2/1-key-exercises/4-random.js

@@ -7,3 +7,7 @@ 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
+
+// num represents a random whole number between 1 and 100, including both 1 and 100.
+// Math.random() generates a random decimal number.
+// Math.floor() rounds the result down to the nearest whole number.

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

@@ -1,4 +1,4 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;

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

@@ -1,5 +1,5 @@
 // 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}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -1,9 +1,6 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().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
+// The original code doesn't work because cardNumber is a number and .slice() cannot be used on a number.
+// Converting cardNumber to a string allows .slice(-4) to return the last 4 characters.

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

@@ -1,2 +1,2 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";

Sprint-2/3-mandatory-interpret/1-percentage-change.js

@@ -2,21 +2,31 @@ 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) How many function calls are there in this file? Write down all the lines where a function call is made
-
-// 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) Identify all the lines that are variable reassignment statements
-
-// 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?
+// a) There are 5 function calls.
+// carPrice.replaceAll(",", "")
+// Number(carPrice.replaceAll(",", ""))
+// priceAfterOneYear.replaceAll(",", "")
+// Number(priceAfterOneYear.replaceAll(",", ""))
+// console.log(`The percentage change is ${percentageChange}`)
+
+// b) The error is on line 5 because there is a missing comma between "," and "".
+// It should be replaceAll(",", "").
+
+// c) The variable reassignment statements are:
+// carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
+// d) The variable declarations are:
+// let carPrice = "10,000";
+// let priceAfterOneYear = "8,543";
+// const priceDifference = carPrice - priceAfterOneYear;
+// const percentageChange = (priceDifference / carPrice) * 100;
+
+// e) Number(carPrice.replaceAll(",", "")) removes the comma from the carPrice string
+// and then converts the result from a string into a number.

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

@@ -11,15 +11,21 @@ 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?
+// a) There are 6 variable declarations:
+// movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours and result.
 
-// b) How many function calls are there?
+// b) There is 1 function call:
+// 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
+// c) movieLength % 60 gives the remainder after dividing movieLength by 60.
+// This represents the number of seconds left after converting the rest into whole minutes.
 
-// d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// d) (movieLength - remainingSeconds) / 60 removes the leftover seconds
+// and divides the remaining seconds by 60 to calculate the total number of whole minutes.
 
-// e) What do you think the variable result represents? Can you think of a better name for this variable?
+// e) result represents the movie length formatted as hours:minutes:seconds.
+// A better variable name could be formattedMovieLength.
 
-// f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// f) The code works correctly for non-negative whole numbers of seconds.
+// If movieLength contains a decimal value, the result may contain decimal seconds.
+// Negative values would also not represent a normal movie duration.

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

@@ -6,6 +6,7 @@ const penceStringWithoutTrailingP = penceString.substring(
 );
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
@@ -20,8 +21,30 @@ 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
+// 1. const penceString = "399p":
+// Initialises a string variable with the value "399p".
+
+// 2. penceString.substring(0, penceString.length - 1):
+// Removes the last character "p" from the string.
+// The result is "399".
+
+// 3. penceStringWithoutTrailingP.padStart(3, "0"):
+// Makes sure the string has at least 3 characters by adding "0" to the start if needed.
+// "399" already has 3 characters, so it remains "399".
+
+// 4. paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2):
+// Takes everything except the last 2 characters.
+// This gives us the pounds part of the price.
+// The result is "3".
+
+// 5. paddedPenceNumberString.substring(paddedPenceNumberString.length - 2):
+// Takes the last 2 characters of the string.
+// This gives us the pence part of the price.
+// The result is "99".
+
+// 6. .padEnd(2, "0"):
+// Makes sure the pence part has 2 characters.
 
-// To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 7. console.log(`£${pounds}.${pence}`):
+// Combines the pounds and pence and prints the formatted price.
+// The final output is £3.99.

Sprint-3/1-key-errors/0.js

@@ -1,13 +1,23 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// I predict an error will occur because str is already the name of the function parameter.
 
 // call the function capitalise with a string input
+capitalise("hello");
+
 // interpret the error message and figure out why an error is occurring
 
 function capitalise(str) {
   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+// The error occurs because str is declared twice in the same scope.
+// str is already a parameter of the capitalise function, so we cannot declare it again using let.
+
+// New code:
+function capitalise(str) {
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return str;
+}
+
+console.log(capitalise("hello"));

Sprint-3/1-key-errors/1.js

@@ -1,7 +1,8 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// I predict an error will occur because decimalNumber is already the name
+// of the function parameter and it is declared again using const.
 
 // Try playing computer with the example to work out what is going on
 
@@ -14,7 +15,15 @@ function convertToPercentage(decimalNumber) {
 
 console.log(decimalNumber);
 
-// =============> write your explanation here
+// The error occurs because decimalNumber is declared twice in the same scope.
+// It is already a parameter of the function, so it cannot be declared again using const.
 
 // 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-3/1-key-errors/2.js

@@ -1,20 +1,25 @@
-
 // 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
+// I predict there will be a syntax error because 3 is a number
+// and a function parameter must be a valid variable name.
 
-function square(3) {
-    return num * num;
-}
+// function square(3) {
+//     return num * num;
+// }
 
-// =============> write the error message here
+// Error message:
+// Identifier expected.
 
-// =============> explain this error message here
+// The error occurs because 3 is being used as the function parameter.
+// A function parameter must be a valid variable name, such as num.
+// The number 3 should be passed into the function as an argument instead.
 
 // Finally, correct the code to fix the problem
 
-// =============> write your new code here
-
+function square(num) {
+    return num * num;
+}
 
+console.log(square(3));

Sprint-3/2-mandatory-debug/0.js

@@ -1,14 +1,24 @@
 // Predict and explain first...
 
-// =============> write your prediction here
+// I predict the multiplication will calculate 320,
+// but the final message will show undefined because the function
+// logs the result instead of returning it.
 
 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 multiply function uses console.log() to display the result,
+// but it does not return a value.
+// A function without a return statement returns undefined.
+// This is why the final message contains undefined.
 
 // 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-3/2-mandatory-debug/1.js

@@ -1,5 +1,7 @@
 // Predict and explain first...
-//  =============> write your prediction here
+
+// I predict the result will be undefined because the return statement
+// does not return the result of a + b.
 
 function sum(a, b) {
   return;
@@ -8,6 +10,14 @@ function sum(a, b) {
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
-// =============> write your explanation here
+// The function returns immediately when it reaches the return statement.
+// Because there is no value after return, the function returns undefined.
+// The line a + b is never reached.
+
 // 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-3/2-mandatory-debug/2.js

@@ -1,7 +1,8 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// I predict that all three console.log statements will show 3
+// because the function uses the global variable num, which is 103.
 
 const num = 103;
 
@@ -14,11 +15,24 @@ 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 output is:
+// 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 getLastDigit function does not have a parameter.
+// It always uses the global variable num, which has the value 103.
+// Therefore, the arguments 42, 105 and 806 are ignored.
+// The last digit of 103 is 3, so the function returns 3 every time.
+
 // 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
+function getLastDigit(number) {
+  return number.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)}`);

Sprint-3/3-mandatory-implement/1-bmi.js

@@ -17,3 +17,7 @@
 function calculateBMI(weight, height) {
   // return the BMI of someone based off their weight and height
 }
+function calculateBMI(weight, height) {
+  const bmi = weight / (height * height);
+  return bmi.toFixed(1);
+}