London | 26-ITP-May | Raihan Sharif | Sprint 1 | Coursework

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

@@ -4,3 +4,6 @@ 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
+
+// It is taking the value of the variable count at line 1, and then adding 1 to it.
+// Then it is assigning that value to the variable count.

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

@@ -5,7 +5,5 @@ 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
-

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(1, lastSlashIndex);
+const ext = base.split(".")[1];
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn

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

@@ -7,3 +7,9 @@ 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
+
+// This code generates a random number between 1 and 100 (inclusive of 100).
+// Math.random() produces a pseudo-random number greater than or equal to 0 and less than 1.
+// That number is multiplied by the total count of possible values we want, in this case 100.
+// The + 1 in (maximum - minimum + 1) ensures that 100 is one of the possible values of num.
+// the + minimum at the end makes 1 the lowest value possible.

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

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

@@ -1,5 +1,7 @@
 // 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}`);
+// need to declare city of birth first.
+
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -1,9 +1,16 @@
 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
+
+// Prediction: there will be an error, cardNumber does not have a slice method.
+// Slice method only applies to strings and arrays
+
+// Result: TypeError: cardNumber.slice is not a function. Which is the expected error.
+
+// Fix: Casting the cardNumber to a string allows us to use the slice method.

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

@@ -1,2 +1,4 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const TwelveHourClockTime = "20:53";
+const TwentyFourHourClockTime = "08:53";
+
+// variable names can't start with a number

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

@@ -12,11 +12,19 @@ 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
+// Total: 5
+// 2 in line 4, 2 in line 5
+// 1 in 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?
+// Error in line 5, missing comma after first arguement in replaceAll.
 
 // c) Identify all the lines that are variable reassignment statements
+// Lines 4, and 5
 
 // d) Identify all the lines that are variable declarations
+// Lines 1, 2, 7, 8
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// replaceAll function returns a new string with all commas removed, so that it is a valid input for Number.
+// Number takes an input and converts it to a number.

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

@@ -1,4 +1,4 @@
-const movieLength = 8784; // length of movie in seconds
+const movieLength = -5784; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
 const totalMinutes = (movieLength - remainingSeconds) / 60;
@@ -12,14 +12,23 @@ 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?
+// 6
 
 // b) How many function calls are there?
+// 1
 
 // 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 in JavaScript. The expression represents the remainder after dividing
+// movieLength by 60, in this case: 24.
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// The total length of the movie in minutes, after taking away the fractional part (the 24 seconds).
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// The exact runtime of the movie, converted from seconds into hours, minutes and seconds format.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// It works with all positive values of movieLength. For negative values, it produces negative hours, minutes, and seconds.
+// This is due to the fact that % is a remainder operator, not a true modulo operator. It always takes the sign of the divided.
+// So if you divide a negative number, the remainder will be negative.

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

@@ -1,4 +1,4 @@
-const penceString = "399p";
+const penceString = "9p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
@@ -25,3 +25,22 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// 3. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+// removes the trailing p so that there's a clean number format to work with.
+
+// 8. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// pad the start so that there's always a character (0) in the pound's place, and the 10th and 100th place of the
+// fractional part (pence). E.g. for 9 pence, the pre-padded number would be "9", by padding it with 0, you get
+// 009, which can easily be formatted as £0.09.
+
+// 9. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+// final two characters will always represent pence, be it "09" for 9 pence, or "90" for 90 pence
+// so the pound part will be anything preceding those two characters.
+
+// 14. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
+// I guess, this is trying to ensure that pence always amounts to at least 2 digits, but it is unnecessary
+// as you're always taking the last two digits and padStart in line 8 ensures that the string always has at least 3 characters.
+
+// 18. console.log(`£${pounds}.${pence}`);
+// this is just adding a pound symbol at the start and joining the pound and pence parts captured earlier with a dot.