London | 26-Jan-ITP | Shuheda Begum | Sprint 2 | Coursework

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

@@ -4,3 +4,7 @@ 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
+// This line (line 3), is updating the value of the count variable. The = operator is an 
+// assignment operator which assigns the value on the right (count + 1) to the variable on the left (count). 
+// count = count + 1; This operation is called increment.
+// An increment means increasing the value of a variable by 1.

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

@@ -4,8 +4,6 @@ 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 = firstName[0] + middleName[0] + lastName[0];
 
-let initials = ``;
-
-// https://www.google.com/search?q=get+first+character+of+string+mdn
-
+// 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

@@ -7,3 +7,16 @@ 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
+
+// Math.random returns a random number between 0 (inclusive) and 1 (exclusive).
+// const minimum = 1; const maximum = 100; +1 so, 100 - 1 + 1 = 100
+// Math.random() * 100 means the decimal number will be multiplied by 100, so the range of possible values is from 0 to 99.9999...
+// Math.floor rounds the number down to the nearest whole number, so the possible values are from 0 to 99.
+// Eg. 12.9 becomes 12, 0.3 becomes 0, 99.9 becomes 99.
+// Brackets(), Multiply*, Function(Math.floor), Addition+
+// 1) Pick a random number between 0 and 1, eg. 0.5
+// 2) Multiply that number by 100, eg. 0.5 * 100 = 50
+// 3) Round that number down to the nearest whole number, eg. Math.floor(50) = 50
+// 4) Add 1 to that number, eg. 50 + 1 = 51
+
+// num represents a random whole number between 1 and 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?
+// The forward slash is used to indicate a comment in JavaScript, so the computer will ignore these lines when running the program.

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

@@ -1,4 +1,10 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+console.log(age);
+
+// The code above will output 34, because we are reassigning the value of age 
+// to be the current value of age plus 1. So, 33 + 1 = 34.
+// The error in the code is that it was trying to reassign a value to a variable 
+// that was declared with let. This is not allowed in JavaScript.

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

@@ -1,5 +1,8 @@
 // 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}`);
+
+// The error happens because cityOfBirth is used before it is defined. JavaScript runs 
+// code from top to bottom, so the variable must be declared first.

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

@@ -1,9 +1,21 @@
-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: The code will not work because slice() is being used on cardNumber, which is a number.
+// The slice() method only works on strings or arrays, not numbers.
+// So I predict JavaScript will throw an error saying that slice is not a function for a number.
+
+const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);
+
+// After running the code, I got the output "4213", which is the last 4 digits of the card number.
+// This is what i expected.
+//testing

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

@@ -1,2 +1,12 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+// const 12HourClockTime = "20:53";
+// const 24hourClockTime = "08:53";
+
+// Variables cannot start with a number.
+// When JavaScript tries to run the code, it throws a SyntaxError.
+// To fix the error we can rename the variable to start with a letter, a 
+// underescore_ or a dollar sign $ instead of a number.
+
+const twelveHourClockTime = "8:53";
+const twentyFourHourClockTime = "08:53";
+
+// I changed the time to match the 12 and 24 hr clock format.

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;
@@ -11,12 +11,49 @@ 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
+// a) How many function calls are there in this file? Write down all the 
+// lines where a function call is made
+
+// There are 5 function calls in this file. They are on lines 1, 2, 4, and 5. 
+// The functions being called are replaceAll() and Number(). 
+// Line 4: replaceAll and Number (2)
+// Line 5: replaceAll and Number (2)
+// Line 10: console.log (1)
+
+
+
+// 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?
+
+// The error is occuring on line 5. It is occuring because there is a missing 
+// comma between the replaceAll "".
+// We can fix this by adding a comma between the two empty strings in the replaceAll 
+// function on line 5, like this: priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));  
+
 
-// 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
 
+// carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+
+
+
 // 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?
+// Lines 1,2,7 and 8.
+// 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(",", "") - Replaces all commas "," in the string with 
+// nothing "". e.g "10,000" becomes "10000".
+// Number() - Converts the resulting string "10000" into the number 10000.
+// The purpose of this is to take a string with commas (like "10,000") and turn 
+// it into a number (10000) that we can do math with.

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

@@ -1,25 +1,78 @@
-const movieLength = 8784; // length of movie in seconds
+//const movieLength = 8784; // length of movie in seconds
 
-const remainingSeconds = movieLength % 60;
-const totalMinutes = (movieLength - remainingSeconds) / 60;
+//const remainingSeconds = movieLength % 60;
+//const totalMinutes = (movieLength - remainingSeconds) / 60;
 
-const remainingMinutes = totalMinutes % 60;
-const totalHours = (totalMinutes - remainingMinutes) / 60;
+//const remainingMinutes = totalMinutes % 60;
+//const totalHours = (totalMinutes - remainingMinutes) / 60;
 
-const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
-console.log(result);
+//const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
+//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?
 
+// There are 6 variable declarations in this program. They are on lines 1, 3, 5, 7, 
+// 9 and 11. The variables being declared are movieLength, remainingSeconds, totalMinutes, 
+// remainingMinutes, totalHours and result.
+
+
+
 // b) How many function calls are there?
 
+// There is 1 function calls in this program. It is on lines 10. The functions is the 
+// console.log().
+
+
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
+// % is the remainder operator.
+// movieLength % 60 - This gives the remainder when movieLength is divided by 60.
+// Since there are 60 seconds in a minute, this tells us how many leftover seconds there are 
+// after counting full minutes.
+// For example, 8784 % 60 = 24. So there are 24 seconds left after counting the minutes.
+
+
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+// movieLength - remainingSecond - This gives the total number of seconds in the movie after 
+// removing the leftover seconds.
+// Divide by 60 - this converst the seconds into total full minutes. eg. (8784 - 24) = 8760, 8760 / 60 = 146.
+
+
+
 // 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
+// The variable result is a string that represents the movie length in hours:minutes:seconds
+// For example: 2:26:24 (2 hours, 26 minutes, 24 seconds)
+// Better name can be movieDurationString.
+
+
+
+// f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? 
+// Explain your answer
+
+// This code will work for all positive integer values of movieLength. It will correctly calculate the hours,
+// minutes and seconds for any length of movie. However, if movieLength is negative or not an integer, the 
+// code may not work as intended. For example, if movieLength is -100, the calculations will not make sense 
+// in the context of a movie length. If movieLength is a decimal, it may also cause issues with the calculations.
+
+const movieLength = 65;
+
+const remainingSeconds = movieLength % 60;
+const totalMinutes = (movieLength - remainingSeconds) / 60;
+
+const remainingMinutes = totalMinutes % 60;
+const totalHours = (totalMinutes - remainingMinutes) / 60;
+
+const formattedHours = String(totalHours).padStart(2, "0");
+const formattedMinutes = String(remainingMinutes).padStart(2, "0");
+const formattedSeconds = String(remainingSeconds).padStart(2, "0");
+
+const movieDurationString = `${formattedHours}:${formattedMinutes}:${formattedSeconds}`;
+
+console.log(movieDurationString); // 00:01:05

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

@@ -25,3 +25,18 @@ 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): creates 
+// a new string variable that contains the original string without the last character (the "p"). 
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"): creates a new 
+// string variable that pads the previous string with leading zeros until it is at least 3 characters 
+// long. eg. "45" becomes "045" and "7" becomes "007".
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2): creates 
+// a new string variable that contains the first part of the padded string, which represents the pounds.
+// It takes all characters except the last two. eg. "045" becomes "0" and "399" becomes "3".
+// 5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0"): 
+// creates a new string variable that contains the last two characters of the padded string, which represents 
+// the pence. It also pads it with trailing zeros if necessary to ensure it is 2 characters long. eg. "045" 
+// becomes "45" and "7" becomes "70".
+// 6. console.log(`£${pounds}.${pence}`): outputs the final price in pounds and pence format to the console. 
+// For example, if penceString is "399p", it will output "£3.99". If penceString is "45p", it will output "£0.45". 
+// If penceString is "7p", it will output "£0.07".

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

@@ -1,13 +1,38 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// I predict when this code runs, there will be a SyntaxError before the function executes. 
+// This is because the identifier 'str' has already been declared.
 
 // call the function capitalise with a string input
+// capitalise("hello");
+
+
 // interpret the error message and figure out why an error is occurring
+// Uncaught SyntaxError: Unexpected identifier 'string' - this is the error message. 
+// This error is occuring because the variable 'str' is being redeclared within the 
+// function, which is not allowed in JavaScript.
+// The duplicate use if 'str' is causing the syntax error.
+
+
+//function capitalise(str) {
+  //let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  //return str;
+//}
+
+// The issue is variable redeclaration.
+// str is the function parameter.
+// let str tries to create a new variable with the same name.
+// JavaScript does not allow redeclaring a variable in the same scope.
+// As a result, the code throws a SyntaxError when it encounters the second 'str' declaration.
+
+// New code without the error:
 
+// 0.js — fully fixed version
 function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
+  if (!str) return str; // handles empty string
+  return str[0].toUpperCase() + str.slice(1);
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+// Test it
+console.log(capitalise("hello")); // should print "Hello"
+console.log(capitalise("world")); // should print "World"
+console.log(capitalise(""));      // should print ""

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

@@ -1,20 +1,32 @@
 // Predict and explain first...
-
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// I predict an error will occur when this program runs because the variable 'decimalNumber' is already declared inside the function 'convertToPercentage' and cannot be redeclared.
 
 // Try playing computer with the example to work out what is going on
+// When the 'function convertToPercentage(decimalNumber)' is created, 
+// Javascript already creates a variable called decimalNumber. then, inside the function, 
+// 'const decimalNumber = 0.5' tries to create another variable with the same name. This 
+// casues a syntax error because you cannot declare two variables with the same name in the same scope. 
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
-  const percentage = `${decimalNumber * 100}%`;
+// function convertToPercentage(decimalNumber) {
+  // const decimalNumber = 0.5;
+  // const percentage = `${decimalNumber * 100}%`;
 
-  return percentage;
-}
+  // return percentage;
+// }
 
-console.log(decimalNumber);
+// console.log(decimalNumber);
 
-// =============> write your explanation here
+// Write your explanation here
+// I redelcared the parameter decimalNumber using const. 
+// I tried to log decimalNumber outside its scope.
+// The variables declared inside the function are not available outside unless they are returned.
 
 // 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)); // "50%"