London | 26-ITP-Jan | Alex Okorefe | Sprint 1 | Coursework

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

@@ -1,6 +1,12 @@
 let count = 0;
 
 count = count + 1;
+console.log(count);
 
 // 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 reassigning the value of the count variable to the result of the expression count + 1.
+// The = operator is the assignment operator, which assigns the value on the right-hand side
+// (the result of count + 1) to the variable on the left-hand side (count).
+// This increments the value of count by 1.

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

@@ -5,7 +5,8 @@ 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 = `${firstName[0]}${middleName[0]}${lastName[0]}`;
 
-// https://www.google.com/search?q=get+first+character+of+string+mdn
+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 +17,10 @@ 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 ext = filePath.slice(filePath.lastIndexOf("."));
+console.log(`the ext part of ${filePath} is ${ext}`);
+
+// https://www.google.com/search?q=slice+mdn

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

@@ -3,7 +3,33 @@ 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
+
+// when first evaluating the full num expression i got the answer 99
+// The second time i got 50 (which means .floor and .random are doing something to change the value of the expression each run)
+
+// The order of operations is as follows:
+
+// 1. The expression inside the parentheses is evaluated first: (maximum - minimum + 1) which gives us 100 - 1 + 1 = 100
+// 2. Then Math.random() is called, which generates a random decimal number the range [0, 1).
+// 3. The result of Math.random() is multiplied by the result of step 1, giving us a random decimal number in the range [0, 100).
+// 4. Math.floor() is then called on the result of step 3, which rounds it down to the nearest integer, 
+//    resulting in a value from the set {0, 1, ..., 99\}
+// 5. Finally, the minimum value (1) is added to the result of step 4, giving us a random integer in the range [1, 100].
+
+// When num = 99
+// math.random gives us 0.98 (or something close to it)
+// 0.98 * 100 = 98
+// math.floor(98) = 98
+// 98 + 1 = 99
+
+// When num = 50
+// math.random gives us 0.49 (or something close to it)
+// 0.49 * 100 = 49
+// math.floor(49) = 49
+// 49 + 1 = 50

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

@@ -1,2 +1,5 @@
-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?
+
+//We solve the problem by commenting out the lines -
+// this means that the computer will ignore them when it runs the program

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 age = 33;
 age = age + 1;
+
+console.log(age);

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

@@ -1,5 +1,14 @@
 // 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}`);
+
+//ReferenceError: Cannot access 'cityOfBirth' before initialization
+
+// This is happening because we are trying to use the variable cityOfBirth
+// before it has been declared and assigned a value.
+
+// Variables declared with let and const can't be accessed before they are initialized.
+
+// To fix this error, we need to declare and assign a value to cityOfBirth before we try to log it to the console.

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

@@ -1,9 +1,19 @@
-const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const cardNumber = "4533787178994213";
+const last4Digits = cardNumber.tostring().slice(-4);
+
+console.log(last4Digits);
 
 // 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
+
+// initial prediction:
+// I don't think the code will work because cardNumber is a number, and the slice method is a string method.
+
+// The error I get is: TypeError: cardNumber.slice is not a function
+
+// This error is happening because the slice method is being called on a number,
+// which does not have the slice method. The slice method is only available for strings and arrays.

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

@@ -1,2 +1,9 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const twelveHourClockTime = "20:53";
+const twentyFourHourClockTime = "08:53";
+
+console.log(twelveHourClockTime, twentyFourHourClockTime);
+
+//SyntaxError: Invalid or unexpected token
+
+// This error is happening because variable names cannot start with a number.
+// To fix this error, we can change the variable names to start with a letter instead of a numbers.

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 +13,32 @@ 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
 
+//There are 5 function/method calls in this file. Lines 4, 5 and 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?
 
+// The error is occurring on line 5:
+// SyntaxError: missing ) after argument list. This is because there is a missing comma between the two arguments
+// (search value & replace value) in the replaceAll function.
+// To fix this problem, we can add a comma between the two arguments.
+
 // c) Identify all the lines that are variable reassignment statements
 
+// These lines include:
+// line 3: let carPrice = "10,000"; to carPrice = Number(carPrice.replaceAll(",", ""));
+// line 4: let priceAfterOneYear = "8,543"; to priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
 // d) Identify all the lines that are variable declarations
 
+// These lines include:
+// line 3: let carPrice = "10,000";
+// line 4: let priceAfterOneYear = "8,543";
+// line 6: const priceDifference = carPrice - priceAfterOneYear;
+// line 7: const percentageChange = (priceDifference / carPrice) * 100;
+
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+// The purpose of this is expression is to search for remove all commas from the string value of carPrice and replace them with an empty string.
+// This converts the CarPrice value from a string to a type number, which we can now perform mathematical operations on.
+// Since the purpose of this program is to calculate the percentage change in the price of a car.
+// We need type number values to perform the necessary calculations.

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

@@ -1,4 +1,4 @@
-const movieLength = 8784; // length of movie in seconds
+const movieLength = true; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
 const totalMinutes = (movieLength - remainingSeconds) / 60;
@@ -13,13 +13,48 @@ console.log(result);
 
 // a) How many variable declarations are there in this program?
 
+// There are 6 variable declarations in this program.
+
 // b) How many function calls are there?
 
+// There is 1 function call in this program.
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
-// d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// The expression movieLength % 60 is using the modulus operator (%) to calculate the remainder when movieLength is divided by 60.
+// In this context, it is calculating the number of seconds that are left over after accounting for the full minutes in the movie length.
+
+// d) Interpret line 4, what does the expression assigned to totalMinutes mean
+
+// It calculates the total number of minutes in the movie by first subtracting the remaining seconds from the total movie length (in seconds)
+// and then dividing the result by 60 (the number of seconds in a minute). This gives us the total number of full minutes in the movie length.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+// The variable result has the value of a template literal that combines the total hours, remaining minutes, and remaining seconds
+// into a string format that represents the length of the movie in hours, minutes, and seconds separated by colons.
+// A better name for this variable could be "formattedMovieLength"
+// to more clearly indicate that it represents the movie length formatted as hours, minutes, and seconds.
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// Test 1: movieLength = 1
+// Expected output: 0:0:1
+// Actual output: 0:0:1
+
+// Test 2: movieLength = -1
+// Expected output: 0:0:-1
+// Actual output: 0:0:-1
+
+// Test 3: movieLength = "3,600"
+// Expected output: type error
+// Actual output: NaN:NaN:NaN
+
+// Test 4: movieLength = true
+// Expected output: 0:0:1
+// Actual output: 0:0:1
+
+// The code will work for all values of movieLength that are of type number or can be coerced to a number (like true which is coerced to 1).
+// This is because arithmetic operation need to be performed on movieLength, and if it is not a number or cannot be coerced to a number,
+// It will result in NaN (Not a Number) for the calculations of totalMinutes, remainingMinutes, totalHours, and ultimately the result variable.

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

@@ -1,4 +1,4 @@
-const penceString = "399p";
+const penceString = "9p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
@@ -12,8 +12,7 @@ const pounds = paddedPenceNumberString.substring(
 );
 
 const pence = paddedPenceNumberString
-  .substring(paddedPenceNumberString.length - 2)
-  .padEnd(2, "0");
+  .substring(paddedPenceNumberString.length - 2);
 
 console.log(`£${pounds}.${pence}`);
 
@@ -25,3 +24,85 @@ 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) : intialises a variable
+//    with the value of the penceString variable with the last character "p" removed.
+
+// a. This is achieved by using the substring method on the penceString variable
+//    the substring method enables the program to manipulate the penceSting variable by targeting and removing characters in the string.
+
+// b. The first argument of the substring method indicates the starting index; (0) which is 399p[0] = "3"
+
+// c. The second argument of the substring method indicates the ending index (penceString.length - 1)
+//    (.length) returns the length of the string object which is 4, and (-1) targets the last character in the string which is "p".
+//
+// d. Therefore, the substring method will return a new string that starts from index 0 and ends at index 3 which is "399"
+
+// e. If const penceString = "1399p" the penceStringWithoutTrailingP variable will have the value "1399"
+//    because the substring method will indicate the starting index as (0 which = "1")
+//    and the ending index as (penceString.length - 1) which is 5 - 1 = 4, which is "p"
+//    therefore it will return a new string that starts from index 0 and ends at index 4 which is "1399"
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0") : initialises a variable
+//    with the value of the penceStringWithoutTrailingP variable with padding added to the start of the string
+//    until it reaches a total length of 3 characters.
+
+// a. This is achieved by using the padStart method on the penceStringWithoutTrailingP variable
+//    the padStart method enables the program to manipulate the penceStringWithoutTrailingP variable
+//    by adding padding to the start of the string until it reaches a specified length.
+
+// b. The first argument of the padStart method indicates the target length of the resulting string which is 3 in this case.
+
+// c. The second argument of the padStart method indicates the string to use to fill or pad which is "0" in this case.
+//
+// d. Therefore, if the penceStringWithoutTrailingP variable has a length of less than 3 characters,
+//    the padStart method will add "0" characters to the start of the string until it reaches a total length of 3 characters.
+//    In this case, since penceStringWithoutTrailingP is "399" which already has a length of 3 characters,
+//    the padStart method will not add any padding and paddedPenceNumberString will also be "399".
+
+// e. if const penceStringWithoutTrailingP = "99" the paddedPenceNumberString variable will have the value "099"
+//    because the padStart method will add one "0" character to the start of the string until it reaches a total length of 3 characters.
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2) : initialises a variable
+//    with the value of the paddedPenceNumberString variable with the last two characters removed.
+
+// a. This is achieved by using the substring method on the paddedPenceNumberString variable
+//    the substring method enables the program to manipulate the paddedPenceNumberString variable by targeting and removing characters in the string.
+
+// b. The first argument of the substring method indicates the starting index; (0) which is 399[0] = "3"
+
+// c. The second argument of the substring method indicates the ending index (paddedPenceNumberString.length - 2)
+//    (.length) returns the length of the string object which is 3, and (-2) targets the last two characters in the string which is "99"
+//
+// d. Therefore it will return a new string that starts from index 0 and ends at index 1 which is "3"
+
+// d. If const paddedPenceNumberString = "099" the pounds variable will have the value "0" because the substring method
+//    will indicate the starting index as (0 which = "0") and the ending index as (paddedPenceNumberString.length - 2)
+//    which is 3 - 2 = 1, which is "9" therefore it will return a new string that starts from index 0 and ends at index 0 which is "0"
+
+// e. if penceString = "1399p" ; const penceStringWithoutTrailingP = "1399" ; const paddedPenceNumberString = "1399"
+//    because the padStart method will not add any padding since the length of penceStringWithoutTrailingP is already 4 characters
+//    which is greater than the target length of 3 characters. therefore the const pounds variable will have the value "13"
+//    because the substring method will indicate the starting index as (0 which = "1") and the ending index as
+//    (paddedPenceNumberString.length - 2) which is 4 - 2 = 2, which is "9" therefore it will return a new string that starts from index 0
+//    and ends at index 1 which is "13"
+
+// 5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2) : initialises a variable
+//    with the value of the last two characters of the paddedPenceNumberString variable
+
+// a. This is achieved by using the substring method on the paddedPenceNumberString variable to extract the last two characters of the string.
+
+// b. The first argument of the substring method indicates the starting index which is (paddedPenceNumberString.length - 2)
+//    which targets the last two characters in the string. The ending index is not provided, so it will extract until the end of the string.
+
+// c. Because paddedPenceNumberString was padded to a minimum length of 3 in step 3, this operation is guaranteed to
+//    return exactly two characters, making further padding unnecessary.
+
+// d. For example, if paddedPenceNumberString is "399", the substring method will extract the last two characters "99".
+//    therefore pence will be "99".
+
+// e. if penceString = "9p" ; const penceStringWithoutTrailingP = "9" ; const paddedPenceNumberString = "009" ;
+//    const pounds = "0" ; const pence = "09" because the substring method will extract the last two characters "09".
+
+// 6. console.log(`£${pounds}.${pence}`) : outputs the final result to the console in the format of "£pounds.pence"
+//    where pounds and pence are the values of the pounds and pence variables respectively.