Cape Town | 26-ITP-Sep | Raees Stevens | Sprint 2 | Coursework/sprint 2

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

@@ -4,3 +4,5 @@ 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
+
+// = in line 3 is used as assignment operator to update count. It evaluates count + 1 using the current count value, then stores the result (1) back into count and overwrites the original count value of 0.  

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

@@ -5,6 +5,11 @@ const 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.
 
-const initials = ``;
+const initials = `${firstName[0]}${middleName[0]}${lastName[0]}`;
+
+console.log(initials);
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
+
+
+

Sprint-2/1-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(dir);
+const lastDotIndex = base.lastIndexOf(".");
+const ext = base.slice(lastDotIndex + 1);
+console.log(ext);
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn 

Sprint-2/1-key-exercises/4-random.js

@@ -7,3 +7,12 @@ 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 is a random whole number between 1 and 100 (inclusive).
+// Math.random() returns a decimal from 0 up to (but not including) 1.
+// (maximum - minimum + 1) is the number of possible values (100),
+// so multiplying gives a decimal from 0 up to (but not including) 100.
+// Math.floor rounds down, giving a whole number from 0 to 99.
+// Adding minimum shifts that range up to 1 to 100.

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

@@ -1,4 +1,7 @@
 // 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-2/2-mandatory-errors/2.js

@@ -1,5 +1,6 @@
 // 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}`);
+

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

@@ -1,9 +1,15 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = String(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
+
+// Card Number is declared as a number and not a string, so slice won't work.
+console.log(last4Digits);
+// Yes this is what I predicted. The error is - cardNumber.slice is not a function.
+// I used String() to convert the number to a string before slicing.
+

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

@@ -1,2 +1,6 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+const twelveHourClockTime = "8:53pm";
+const twentyFourhourClockTime = "20:53";
+
+console.log(twelveHourClockTime);
+console.log(twentyFourhourClockTime);
+

Sprint-2/3-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;
@@ -12,11 +12,27 @@ 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
+// There are 5 function calls. 
+// carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// console.log(`The percentage change is ${percentageChange}`);
+
 
 // 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 coming from line 5. There is a separator missing from the function call. Insert a comma to fix the problem.
 
 // c) Identify all the lines that are variable reassignment statements
+// Line 4 carPrice = Number(carPrice.replaceAll(",", ""));
+// Line 5 priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
 
 // d) Identify all the lines that are variable declarations
+// Line 1 let carPrice = "10,000";
+// Line 2 let priceAfterOneYear = "8,543";
+// Line 7 const priceDifference = carPrice - priceAfterOneYear;
+// Line 8 const percentageChange = (priceDifference / carPrice) * 100;
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// carPrice.replaceAll(",", "") removes every comma from the string, turning "10,000" into "10000".
+// Number(...) then converts that string into the number 10000.
+// The purpose is to turn a formatted price string into a real number so it can be used in calculations.
+// Without the commas removed, Number("10,000") would return NaN.

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

@@ -12,14 +12,25 @@ 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.
 
 // b) How many function calls are there?
+// There is 1 function call.
 
 // 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. It returns what is left over after dividing one number by another.
+// movieLength % 60 gives the seconds left over once all the full minutes are taken out of the movie length.
+// 8784 % 60 = 24, because 8784 seconds is 146 full minutes with 24 seconds left over.
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// It subtracts the leftover seconds from the movie length, leaving a number that divides evenly by 60
+// (8784 - 24 = 8760), then divides by 60 to get the number of whole minutes (8760 / 60 = 146).
+// So totalMinutes is the total number of complete minutes in the movie.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// The variable result represents the total length of the movie in hours, minutes and seconds. A better name would be movieLengthHHMMSS.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+

Sprint-2/3-mandatory-interpret/3-to-pounds.js

@@ -25,3 +25,28 @@ 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): 
+// Takes the characters from index 0 up to (but not including) the last character.
+// penceString.length is 4, so this is substring(0,3), resulting in "399". 
+// The purpose is to remove the "p" so only digits remain.
+
+// 8. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0")
+// Adds "0"s to the start until the string is at least 3 characters long.
+// The purpose is to guarantee at least one digit for pounds and two digits for pence.
+
+// 9. const pounds = paddedPenceNumberString.substring(0,paddedPenceNumberString.length - 2);
+// The purpose is to make the pounds all the digits before the last two, by taking everything except the last two characters: substring(0,1), giving "3"
+
+// 14. const pence = paddedPenceNumberString .substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
+// substring(1) takes from index 1 to the end, giving "99".
+// padEnd(2, "0") adds "0"s to the end until it is two characters long, so "99" stays "99".
+// The purpose is too ensure the pence are always the last two digits.
+// The padEnd does not change anything here since line 8 already guarantees at leas 3 characters, so the last two characters always exist.
+
+// 18. console.log(`£${pounds}.${pence}`);
+// Call function using a template literal to combine "£", the pounds, a ".", and the pence, then prints "£3.99".
+
+
+
+