West Midlands | 25 Sep ITP | Iswat Bello | Sprint 1 | Module Structuring and Testing Data

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

@@ -1,6 +1,11 @@
 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
+
+//Answer
+// The third line is a statement that reassigns the value of count to count + 1.
+// The assignment operator (=) updates the variable count with a new value.

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.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

@@ -11,13 +11,16 @@
 
 const filePath = "/Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt";
 const lastSlashIndex = filePath.lastIndexOf("/");
+console.log(lastSlashIndex);
 const base = filePath.slice(lastSlashIndex + 1);
 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(dir);
+const ext = filePath.slice(lastSlashIndex + 1) ;
+console.log(ext);
 
 // https://www.google.com/search?q=slice+mdn

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

@@ -2,8 +2,32 @@ const minimum = 1;
 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
+
+//Answers
+// num is a constant variable that stores a random integer between the minimum and maximum values (inclusive), generated using Math.random() and Math.floor()
+
+
+
+// Math.random()
+// This expression gives you a random decimal number between 0 and 1.
+// It could be something like 0.25 or 0.879, but it will never reach 1.
+
+// (maximum - minimum + 1)
+// This expression calculates how many numbers are in the range you want.
+// For example, if your range is 1 to 100, the result is 100 because there are 100 possible values.
+
+// Math.random() * (maximum - minimum + 1)
+// This expression multiplies the random decimal by your range.
+
+
+// Math.floor(...)
+// This expression rounds the number down to the nearest integer.
+// For example, 37.6 becomes 37, and 99.9 becomes 99.
+
+// + minimum
+// Variable minimum is added to the expression "Math.floor(Math.random() * (maximum - minimum + 1))" and the the value is stored inside the variable num

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

@@ -1,2 +1,11 @@
-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?
+
+// Interpretation:
+// The error "SyntaxError: Unexpected identifier 'is'" means that JavaScript found the word "is", but it didn’t make sense in that position. 
+// It wasn’t valid code that JavaScript could understand.
+
+// Why the error occurred:
+// The error occurred because the sentence was written as plain text instead of a comment.
+// To fix it, the sentence should be written as a comment (by adding // at the beginning) so that JavaScript ignores it.
+

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

@@ -2,3 +2,7 @@
 
 const age = 33;
 age = age + 1;
+
+
+// The error message is "Assignment to constant variable", which means that a variable declared with the 'const' keyword
+//  cannot be reassigned to a new value after its initial declaration.

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

@@ -3,3 +3,5 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// The error message 'Cannot access 'cityOfBirth' before initialization' occured because the 'const' variable was used before it was declared. 

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

@@ -1,9 +1,22 @@
-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
+
+
+// Answer
+// The code will not work because the slice method in javascript only works on a string or an array. 
+// The data type of the value stored in the variable cardNumber is a number and for this reason, the code will return an error.
+// After running the code, it gave an error " TypeError: cardNumber.slice is not a function"
+// My prediction and the error align.
+// To update the code, I will convert the variable cardNumber to a string first then use slice() method after
+
+const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);

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";
+
+// console.log(12HourClockTime , 24hourClockTime);
+
+// Answer
+// After running the code, it gave an error message "SyntaxError: Invalid or unexpected token". 
+// This error means that Javascript was unable to read the code because a variable name cannot start with a number
+// I can fix this code by removing the numbers from the start of the variable name
+
+const HourClockTime = "20:53";
+const hourClockTime = "08:53";

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

@@ -1,8 +1,8 @@
 let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
-carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+carPrice = Number(carPrice.replaceAll("," ,""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ,""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -12,11 +12,17 @@ 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
+// Answer: There are five function calls in this file. function was called on line 4 (twice), line 5 (twice) and 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?
+// Answer:
+// After running the code, the error occurred because a comma was missing between the quotation marks on line 5. I fixed it by adding the missing comma.
 
 // c) Identify all the lines that are variable reassignment statements
+// Answer: Variable reassignment statements occurred on lines 4 and 5
 
 // d) Identify all the lines that are variable declarations
+// Answer: Variable declarations occurred on lines 1, 2, 7, and 8.
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// Answer: The .replaceAll() method runs first to find all the comma in the variable carPrice and replace them with nothing then the Number() functions  runs to convert the value to a number data type

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

@@ -1,4 +1,4 @@
-const movieLength = 8784; // length of movie in seconds
+const movieLength = 8974; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
 const totalMinutes = (movieLength - remainingSeconds) / 60;
@@ -12,14 +12,21 @@ 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?
+//Answer: There are six variable declarations in this program
 
 // b) How many function calls are there?
+// Answer: There is only one function call in the program
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// Answer: The expression movieLength % 60 represents the remainder when  movieLength is divided by 60
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// Answer: The expression assigned to totalMinutes subtracts the leftover seconds from the movieLength and divide it by 60 to get the totalMinutes.
+// This gives the total whole minutes of the movie without the leftover seconds.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// Answer: The variable result represents the time in hours, minutes and seconds. A better name for the variable could be totalTime
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// Answer: I tried different positive values of movieLength and the code worked for all but result variable returned a negative value when I tried a negative number as the variable movieLength

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

@@ -25,3 +25,168 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// Answer
+const penceString = "399p"
+// declares a variable penceString and assigns a value "399p" to it.
+
+const penceStringWithoutTrailingP = penceString.substring(
+  0,
+  penceString.length - 1
+);
+// Step-by-step breakdown
+// 1. const
+
+// What it means:
+// const is short for constant.
+// It’s a keyword in JavaScript used to declare a variable — a named place in memory where we store a value.
+
+// What makes it special:
+// Once you assign a value to a const variable, you cannot reassign it later.
+
+// 2. penceStringWithoutTrailingP
+
+// What it is:
+// This is the name of the variable we’re creating.
+
+
+// 3. =
+
+// What it means:
+// The equals sign here means assignment, not comparison.
+// It tells JavaScript: “Store the value on the right-hand side into the variable on the left-hand side.”
+
+// So, penceStringWithoutTrailingP will hold whatever value comes from the code on the right side.
+
+// 4. penceString
+
+// What it is:
+// This is a variable that was created earlier in the code:
+
+// 4. .substring(...)
+
+// What it is:
+// .substring() is a built-in method (a function that belongs to strings) in JavaScript.
+
+// What it does:
+// It extracts a section (or slice) of a string, starting and ending at specific positions (index numbers).
+
+// The first number is where to start (inclusive).
+
+// The second number is where to stop (exclusive, it doesn’t include that index).
+
+// ( 0, penceString.length - 1 )
+
+// These are the arguments (inputs) given to the substring() function.
+
+// Let’s understand each one:
+
+// 0
+
+// This means: “Start from the very first character of the string.”
+// In JavaScript, string positions start counting at 0, not 1.
+
+// penceString.length
+
+// .length is a property (not a function).
+// It gives the number of characters in the string.
+
+// For "399p", penceString.length is 4.
+
+// penceString.length - 1
+
+// This means “one less than the total length.”
+
+// 4 - 1 = 3.
+
+// So we’re telling JavaScript: “Stop right before the last character.”
+
+// Putting it all together:
+// penceString.substring(0, penceString.length - 1) means “Take the text in penceString, start at position 0, and stop right before the last character.”
+// So for "399p", it returns "399" — it removes the final p.
+// The variable penceStringWithoutTrailingP will now contain: "399"
+
+const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// Step-by-step breakdown
+// 1. const
+
+// Keyword meaning:
+// const is short for constant.
+// It tells JavaScript that we’re creating a new variable whose value cannot be changed later.
+
+// Why use it here?
+// We only need to store the processed result; we’re not planning to change it again.
+
+//  2. paddedPenceNumberString
+
+// This is the variable’s name.
+
+// 3. =
+
+//  equals sign here is the assignment operator.
+
+// It means “store the result on the right-hand side into the variable on the left-hand side.”
+
+// 4. penceStringWithoutTrailingP
+
+// This is another variable that was defined earlier in the program.
+
+// It holds a string like "399", "50", or "5", after removing the “p” at the end of the original price (like "399p" → "399").
+
+// 5. .padStart(3, "0")
+
+// This is a string method — something you can call on a string to make it do something.
+
+// Let’s break it down further:
+
+// a) The dot (.)
+
+// The dot connects the variable (penceStringWithoutTrailingP) with a method (a built-in action it can perform).
+
+// In English: “Hey JavaScript, take this string and do the padStart operation on it.”
+
+// b) padStart(...)
+
+// This is the method name.
+
+// It “pads” the start (the beginning) of a string with extra characters until it reaches a certain length.
+
+// c) The parentheses (3, "0")
+
+// These are the arguments — pieces of information you pass to the method.
+
+// The first argument (3) means:
+// “Make the string at least 3 characters long.”
+
+// The second argument ("0") means:
+// “If it’s shorter than that, add zeros ("0") at the start.”
+
+// Putting it all together
+const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// When JavaScript checks the length, it sees that it’s already 3 characters long, so it doesn’t add any zeros.
+// the result "399" is stored in the variable "paddedPenceNumberString"
+
+const pounds = paddedPenceNumberString.substring(
+  0,
+  paddedPenceNumberString.length - 2
+);
+// paddedPenceNumberString.length means the length of the character "399" is 3.
+// paddedPenceNumberString.length - 2 means 3 - 2 = 1
+// paddedPenceNumberString.substring(0 , 1) means take everything from position 0 up till position 1 exclusive. This will return 3
+// const pounds means store the value 3 inside the variable pounds.
+
+const pence = paddedPenceNumberString
+  .substring(paddedPenceNumberString.length - 2)
+  .padEnd(2, "0");
+// paddedPenceNumberString.length means the length of the character "399" is 3.
+// paddedPenceNumberString.length - 2 means 3 - 2 = 1
+// .substring(paddedPenceNumberString.length - 2) means .substring(1) which means take everything from positon 1 to the end. This returns 99
+// .padEnd(2, "0") means make sure the string has at least two characters. If not, add zeros ("0") at the end. for this exercise, 99..padEnd(2, "0") will return 99
+// so, const pence means variable pence will store the value 99
+
+console.log(`£${pounds}.${pence}`);
+// console meaans terminal and log means print or show this message.
+// `£${pounds}.${pence}` is a literal template which means £3.99
+// so, print £3.99 to the terminal
+
+