London | 26-ITP-May | Alex Jamshidi | 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
+
+// Line 3 is reassigning the variable 'count' to a new value. The new value that 'count' will take on is the existing value plus 1.
+// Given count is assigned a value of 0 in line 1, after running line 3 the value of count would be expected to be 1.

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

@@ -5,7 +5,6 @@ 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 = ``;
+let initials = firstName.charAt(0) + middleName.charAt(0) + lastName.charAt(0);
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
-

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

@@ -17,7 +17,14 @@ 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 lastDotIndex = filePath.lastIndexOf(".");
 
-// https://www.google.com/search?q=slice+mdn
+const dir = filePath.slice(1, lastSlashIndex);
+const ext = filePath.slice(lastDotIndex);
+
+// Checks
+
+console.log(`The directory part of ${filePath} is ${dir}`);
+console.log(`The extension part of ${filePath} is ${ext}`);
+
+// https://www.google.com/search?q=slice+mdn

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

@@ -7,3 +7,44 @@ 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
+
+console.log(num);
+
+// num returns a value of 60, running it again returns a value of 15, looking at the code I see a .random() function
+// I can make a hypothesis that this returns a random number of some kind, hence the inconsistent result
+
+// Let's find out...
+// Code in inner-most brackets is evaluated first
+// I would expect (maximum - minimum + 1) to be evaluated first (100 - 1 + 1) would equal 100
+
+console.log(maximum - minimum + 1);
+
+// the result was 100
+// this part of the code is then multiplied by Math.random()
+
+console.log(Math.random());
+
+// running this code many times, it appears Math.random() returns a random number between 0 and 1
+// checking documentation online, this is correct (actually between 0 and 0.99999999999)
+// therefore Math.random() * (maximum - minimum + 1) should return a random number between 1 and 100
+
+console.log(Math.random() * (maximum - minimum + 1));
+
+// It does, it returns it with many decimal places, the result of num didn't have any decimal places
+// The next part of the code that is run is Math.floor, let's see what this does
+
+const number = Math.random() * (maximum - minimum + 1);
+console.log(number);
+console.log(Math.floor(number));
+
+// because Math.random() creates a new random number every time it is run, I had to set the
+// result to a variable so I can use the same number in multiple functions
+// When number is 87.52, Math.floor is 87, when number is 70.02, math.floor is 70
+// The function Math.floor appears to be rounding down
+// Checking the documentation, this is true, it returns the largest integer <= the given number
+
+// Therefore Math.floor(Math.random() * (maximum - minimum + 1)) must give random numbers between 0 and 99
+// The final part is the addition of minimum (+1)
+
+// Therefore I can see this code produces a random whole integer between minimum and maximum
+// Which in this case is an integer between 1 and 100

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

@@ -1,2 +1,4 @@
-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?
+
+// I commented out the code so it is not run by the computer using '//'

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

@@ -2,3 +2,8 @@
 
 const age = 33;
 age = age + 1;
+
+// The error is TypeError: Assignment to constant variable.
+// This is occurring as a constant variable cannot be reassigned
+// line 4 is trying to reassign the constant variable age
+// This could be navigated by using let instead of const, or assigning a new variable name for age + 1

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

@@ -3,3 +3,8 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// error message: ReferenceError: Cannot access 'cityOfBirth' before initialization
+// this is occurring as the computer runs the code from top to bottom
+// the variable cityOfBirth is assigned in line 5 but is trying to be run in line 4
+// this could be fixed by swapping the lines around

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

@@ -1,9 +1,21 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = String(cardNumber).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
+
+// .slice needs to act on a string not a number, so I would expect something like 'incorrect input' as an error
+
 // 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?
+
+// TypeError: cardNumber.slice is not a function
+// This is not exactly the words I expected the error to say but is correctly identifying the same error
+// I think it is saying that cardNumber.slice is not a function of a number, hence the TypeError
+
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value
+
+// I converted cardNumber to a string and error resolved and it return the correct output

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

@@ -1,2 +1,6 @@
 const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const 24hourClockTime = "08:53";
+
+// The error: SyntaxError: Invalid or unexpected token
+// This occurs as a variable cannot start with a number (it can include a number)
+// Renaming to something like ClockTime12hour would solve this

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 calls, 2x (lines 4 and 5), 1x (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: SyntaxError: missing ) after argument list   (Line 5)
+// The arguments in the replaceAll function need to be comma separated, the difference can be seen from line 4 where the code
+// did not hit an error, adding in that comma will solve the error
+
 // 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 and 8
+
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+// It looks like the function is removing the commas (by replacing them with nothing) from the string
+// so there are only numbers left and then converting it into a Number data type
+
+console.log(carPrice);
+
+// I commented out the line of code with an error and ran the code to confirm, it returned 10000
+// I can check it is a number by running a math operation on it
+
+console.log(carPrice * 2);
+
+// result as expected

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

@@ -1,4 +1,4 @@
-const movieLength = 8784; // length of movie in seconds
+const movieLength = 5.345345; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
 const totalMinutes = (movieLength - remainingSeconds) / 60;
@@ -13,13 +13,35 @@ console.log(result);
 
 // 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 a modulus operator
+// It acts as a divisor, but instead of returning the resultant division, it returns the remainder
+// So movieLength % 60 divides the movieLength into whole minutes and returns however many seconds remain
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+// It is giving the total number of minutes of the movieLength to the nearest whole number (rounded down)
+// It does this by finding removing the remainder of seconds from the total movie length to give the largest
+// movieLength in seconds that is still exactly divisible by 60, then dividing by 60 to give it in minutes
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+// It looks to return a string that breaks the movie length into hours, minutes and seconds that is easier to read/understand
+// (at least for a human)
+// a better variable name may be something like formattedTime
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// Yes
+// The code is using basic mathematical operators, it works even with extremely small or large numbers, it works with 0, it even
+// works with negative numbers, although that is a little nonsensical, it may be better to return an error or undefined in that case
+// For very large numbers it would return a high number of hours, which one may want to then convert to days, or have a max limit
+// It all depends on what the use case for the code is

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

@@ -25,3 +25,47 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+console.log(penceStringWithoutTrailingP);
+
+// 3. const penceStringWithoutTrailingP = penceString.substring(
+// initialises a string variable with value "399" by using function substring on penceString
+
+// 4.   0,
+// first argument for substring, taking part of the string starting from the first letter
+
+// 5.   penceString.length - 1
+// second argument for substring, taking the string up until the 3rd letter
+// done by taking the whole string length (.length) of 4 and removing 1 (this removes the 'p')
+
+// 6. );
+// closes the arguments for the function
+
+console.log(paddedPenceNumberString);
+
+// 8. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// Ensures the string is at least 3 in length, and if not adds zeros to the front
+// This is to ensure later calculations don't return negative values
+
+// 9-12. const pounds = paddedPenceNumberString.substring(
+//  0,
+//  paddedPenceNumberString.length - 2
+// );
+// Performing same function as lines 3 to 6, taking the padded string and removing the last two digits
+// these are the digits representing pence, leaving a string that represents pounds and intialising
+// that as a pounds variable of 3
+
+// 14. const pence = paddedPenceNumberString
+// intialising new pence variable
+
+// 15.  .substring(paddedPenceNumberString.length - 2)
+// performing substring function on the padded string this time for pence by starting the substring
+// from the penultimate (-2) character of the padded string length
+
+// 16. .padEnd(2, "0");
+// ensures the pence string is at least 2 characters long, adding a zero to the start if not
+// closing this function returns 99 to the variable pence
+
+// 18. console.log(`£${pounds}.${pence}`);
+// takes the pounds and pence variables and prints them to the log as a string with a decimal divider and added pound sign
+// at the start: £3.99