I completed 4 exercises of week 1

- Key exercises: count, initials, paths, random numbers
- Mandatory errors: fix all 5 error files (0.js - 4.js)
- Mandatory implementations: percentage change, time format, currency conversion
- Stretch goals: Chrome console and objects exploration

Author: wankoak

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

@@ -2,5 +2,12 @@ let count = 0;
 
 count = count + 1;
 
+console.log(count); // should print 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
+
+
+// On line 3, the code `count = count + 1;` updates the value of the variable `count`. JavaScript first takes the current value stored in `count`, adds `1` to it, and then assigns the new result back into the same variable.
+// The `=` symbol here is the **assignment operator**. It does not mean “equals” in mathematics. Instead, it means “take the value on the right-hand side and store it in the variable on the left-hand side.”
+// After this line runs, `count` now contains the value `1` instead of `0`.

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

@@ -5,7 +5,9 @@ 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]}`;
+
+console.log(initials); // should print "CKJ"
 
 // 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); // dir part is "/Users/mitch/cyf/Module-JS1/week-1/interpret"
+const ext = base.slice(base.lastIndexOf(".")); // ext part is ".txt"
+
+console.log(`The dir part of ${filePath} is ${dir}`); // print: The dir part of /Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt is /Users/mitch/cyf/Module-JS1/week-1/interpret
+console.log(`The ext part of ${filePath} is ${ext}`); // print: The ext part of /Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt is .txt
 
 // https://www.google.com/search?q=slice+mdn

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

@@ -3,7 +3,22 @@ const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 
+console.log(num); // Will output numbers like: 5, 42, 87, 100, etc.
+
 // 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
+
+// Math.random() generates a random decimal between 0 (inclusive) and 1 (exclusive)
+// Examples: 0.1, 0.5, 0.99
+// (maximum - minimum + 1) calculates the range size
+// 100 - 1 + 1 = 100
+// Math.random() * 100 creates numbers from 0 to 99.999...
+// Examples: 0.1 × 100 = 10, 0.5 × 100 = 50, 0.99 × 100 = 99
+// Math.floor() rounds down to the nearest integer
+// Results in integers from 0 to 99
+// + minimum shifts the range
+// Adds 1 to move from 0-99 to 1-100
+// The expression generates a random integer between the minimum value (1) and the maximum value (100), inclusive of both endpoints.
+// Final Answer: num is a random integer from 1 to 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?
+
+// We can use comments to "comment out" these lines

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 +1,5 @@
 // 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}`); // moved the console.log below const

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);
+
+console.log(last4Digits); // should print 4213
 
 // 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
+
+
+// Before running the code, I predicted: The code will throw an error because cardNumber is defined as a number (not a string), and numbers don't have a .slice() method.
+// The .slice() method is only available on strings and arrays, not on number primitives
+// To fix the code, we need to convert the number to a string first, then use .slice()

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";
+
+// updated the variable names to be more descriptive

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(",", "")); // Fixed syntax error by adding missing comma
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -20,3 +20,40 @@ console.log(`The percentage change is ${percentageChange}`);
 // d) Identify all the lines that are variable declarations
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+
+ // Answers 
+
+// a) Function Calls (5 total):
+
+// carPrice.replaceAll(",", "") (Line 3)
+// Number() (Line 3)
+// priceAfterOneYear.replaceAll(",", "") (Line 4)
+// Number() (Line 4)
+//console.log() (Line 8)
+
+// b) Error Fix:
+
+// Error line: Line 4 - missing comma in .replaceAll("," "")
+// Fix: Change to .replaceAll(",", "")
+// Error type: SyntaxError: missing ) after argument list
+
+// c) Variable Reassignments:
+
+// carPrice = Number(carPrice.replaceAll(",", "")) (Line 3)
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", "")) (Line 4)
+
+// d) Variable Declarations:
+
+//let carPrice = "10,000" (Line 1)
+//let priceAfterOneYear = "8,543" (Line 2)
+// const priceDifference = carPrice - priceAfterOneYear (Line 6)
+// const percentageChange = (priceDifference / carPrice) * 100 (Line 7)
+
+// e) Expression Purpose:
+
+// Number(carPrice.replaceAll(",", "")) converts a formatted currency string with commas into a numeric value for mathematical calculations:
+// Removes commas: "10,000" → "10000"
+// Converts to number: "10000" → 10000
+
+// Output: The percentage change is 14.57 (14.57% price decrease)