Complete sprint 1 exercises and fix errors in interpretation tasks

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

@@ -3,4 +3,9 @@ let count = 0;
 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 Three increases the value of count by 1.
+The `=` sign here is the assignment operator, not a comparison.
+It takes the value on the right-hand side (count + 1)
+and stores it back into the count variable on the left.
+*/

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

@@ -2,10 +2,10 @@ let firstName = "Creola";
 let middleName = "Katherine";
 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 = firstName[0] + middleName[0] + lastName[0]; // Get the first letter of each name and combine them
 
-let initials = ``;
-
-// https://www.google.com/search?q=get+first+character+of+string+mdn
+console.log(initials); // this will print "CKJ"
 
+// we can also use firstName.charAt(0);  // "C"
+// but using "[]" is more easy and modern
+// "+" joins characters

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

@@ -14,10 +14,5 @@ const lastSlashIndex = filePath.lastIndexOf("/");
 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 = ;
-
-// https://www.google.com/search?q=slice+mdn
+const dir = filePath.slice(0, lastSlashIndex); // This gives us everything up to (but not including) the last /
+const ext = base.slice(dotIndex); //  gives ".txt"

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;
 
-// 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
+// In this code, the variable num represents a random whole number between 1 and 100, including both 1 and 100.
+/*
+Breakdown:
+- Math.random() gives a number from 0 (inclusive) to 1 (exclusive), like 0.57
+- (maximum - minimum + 1) calculates how many whole numbers we need (e.g. 100 - 1 + 1 = 100)
+- Multiplying the random decimal by the range gives a number from 0 up to just below 100
+- Math.floor(...) turns that into a whole number (e.g. 78.2 becomes 78)
+- Adding minimum (1) shifts it into the correct final range (1–100 inclusive)
+*/
+/*
+Order of evaluation:
+1. (maximum - minimum + 1) → calculate the range (e.g., 100 - 1 + 1 = 100)
+2. Math.random() → returns a decimal from 0 up to (but not including) 1
+3. Multiply the random decimal by the range → gives a decimal between 0 and range
+4. Math.floor(...) → rounds down to the nearest whole number
+5. + minimum → shifts the value up so it starts from the minimum value
+
+Final result: a random whole number between minimum and maximum, inclusive.
+*/

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 +1,9 @@
 // trying to create an age variable and then reassign the value by 1
 
 const age = 33;
+age = age + 1; // this will cause an error because we can't reassign the value of a const(constant)variable
+
+let age = 33;
 age = age + 1;
+console.log(age);
+// when we want to reassign the variable to a new value we have to use let

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

@@ -3,3 +3,10 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+// this gives an error because the console.log comes before const or let variable and this kind of error is called "TDZ"
+/*Even though you declared cityOfBirth with const, the console.log comes before that declaration. So JavaScript says:
+"Hey! You’re trying to use cityOfBirth, but it hasn’t been initialized yet!" *\
+// so to make it work i only need to change their position like below
+
+const cityOfBirth = "Bolton"
+console.log(`I was born in ${cityOfBirth}`)

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

@@ -1,9 +1,17 @@
 const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.slice(-4); // this will give error as cardNumber.slice is not a function since .slice() only works with strings and arrays
+
+//.slice() is a method that works on strings and arrays, not on numbers.
+
+const cardNumber = "4533787178994213"; // since i changed the number to a string now .slice() will become a function and works perfectly
 const last4Digits = cardNumber.slice(-4);
+console.log(last4Digits); // will print the last 4 digits which are "4213"
+
+// or i can use other options as well
+
+const cardNumber = 4533787178994213;
+const last4Digits = String(cardNumber).slice(-4);
+
+console.log(last4Digits); // Output: "4213", this will give as the number as a string
 
-// 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
+//.slice() always return a value as a string

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

@@ -1,2 +1,7 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const 12HourClockTime = "20:53";// variable name can not start with a number
+const 24hourClockTime = "08:53";// variable name can't start with a number 
+
+// to correct this code i have to begin the variable name with either letter or underscore character 
+
+clockTime12Hour="20:53"// even though "20:53" is not in 12 hour format our code will run as long as the variable is defined 
+clockTime24Hour="08:53"

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

@@ -13,10 +13,34 @@ 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 in the above code and we can find them in 
+- line 4: Number(carPrice.replaceAll(",", "")
+- line 5: Number(priceAfterOneYear.replaceAll("," "")
+- line 10: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?
+/* line 5:  priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+                                                                    ^^^
+SyntaxError: missing ) after argument list *\
 
 // c) Identify all the lines that are variable reassignment statements
 
+/* line 4 and line 5 
+carPrice = Number(carPrice.replaceAll(",", ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));*\
+
+
+
 // d) Identify all the lines that are variable declarations
+/* Line 1,2,7 and 8 basically any line with let and const  *\
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+/* carPrice.replaceAll(",","") this will replace "," with this "" which is removing the comma so in our code "10,000" will be replaced by "10000"
+this is because we cant do math with a string with a comma so we need to remove the comma before doing the math. so after removing the comma from 
+the string we left with Number(), this function will convert the string into number so that we can do our math. 
+IN SUMMARY
+Number("10,000") will actually return NaN (Not a Number)
+❗ Because the comma confuses it
+
+So you must remove the comma first, then convert to number. *\

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

@@ -13,13 +13,28 @@ console.log(result);
 
 // a) How many variable declarations are there in this program?
 
+// there are 6 variable declaration are there,anything that starts with let and const considered as a variable declaration
+
 // b) How many function calls are there?
 
+// there is only one function call, which is console.log(). a function has to be like this functionName()
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
+
+// The remainder (%) operator returns the remainder left over when one operand is divided by a second operand. It always takes the sign of the dividend.
+// movieLength % 60 means How many seconds are left after dividing movieLength by 60?"
+// movieLength % 60 gives you the remaining seconds after converting as many seconds as possible into whole minutes.
+
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+// it means take the number of full seconds that can be evenly split into minutes, and convert that to minutes.
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+// it represents a time format like this HH:MM:SS and a better name that suits the variable is timeFormat
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// Yes, the code will work for all non-negative integers,i tried using different values starting from 0,1 amd going upto million and the code works
+// The code correctly takes a number of seconds (movieLength) and converts it into a time format: hours, minutes, and seconds — then displays it as a string like H:M:S."

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

@@ -24,4 +24,36 @@ console.log(`£${pounds}.${pence}`);
 // Try and describe the purpose / rationale behind each step
 
 // To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 1. const penceString = "399p": initializes a string variable with the value "399p"
+
+// 2. const penceStringWithoutTrailingP= Removes the trailing "p" character so we are left with just the numeric part: "399"
+// to do a step by step breakdown: .substring(start,End), which "0" represents the start index "0" and penceString.length-1 is a common way to get the index of the last character in any string.
+// penceString.length - 1 → length of "399p" is 4, so 4 - 1 = 3
+// so now .substring(start,End)  extracts characters from index 0 to index 3 (not including 3).
+// "399p".substring(0, 3) // returns "399", since counting starts from index 0
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// .padStart(3, "0") ensures the string is at least 3 characters long and If it's shorter (like "5" or "99"), it pads it from the start with zeros.
+// example "5"= 005 or "88"= 088 it makes sure the characters are always three by adding zro when its shorter
+// in this case "399" stays "399"
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+// Gets all but the last two digits
+// paddedPenceNumberString = "399"-length is 3, so 3 - 2 = 1
+// substring(0, 1) means get characters from index 0 up to index 1 (not including 1)
+// "399".substring(0, 1) → "3" its purpose is to extract the pound from the string like this 399p= £3.99
+
+// 5.const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length-2).padEnd(2,"0")
+//  (paddedPenceNumberString.length - 2) takes the last two digits of the string "399"- 3-2=1
+// .substring(1): this is saying give me the part of the string starting at this index, and go to the end
+// so in "399" index 1 is 9 so we will get 99, which gives us index 1 to the end
+// .padEnd(2, "0"): Makes sure the result has at least 2 digits, padding with "0" if it’s too short like "5"=05,makes it two digit
+//"399" → last two digits → "99" → no padding needed → stays "99"
+//Extracts the pence part of the string — always exactly 2 digits to match £x.xx format.
+
+// 6. console.log(£${pounds}.${pence});
+// Combines the two parts i have built:pounds and pence then uses template literal syntax to insert the variables into a string
+// and finally prints it like this £3.99
+
+// Overall Purpose of the Code:
+// This code takes a string like "399p" (meaning 399 pence) and formats it as a proper British currency string like £3.99.It handles other cases too, like "5p" → £0.05 or "99p" → £0.99, thanks to the padding.

age.js

@@ -0,0 +1,3 @@
+let age= 33
+age = age + 1 
+console.log(age)

cardNumber.js

@@ -0,0 +1,3 @@
+const cardNumber ="4533787178994213"
+const last4Digits = cardNumber.slice(-4);
+console.log(last4Digits)

cardNumber2.js

@@ -0,0 +1,4 @@
+const cardNumber = 4533787178994213;
+const last4Digits = String(cardNumber).slice(-4);
+
+console.log(last4Digits)

cityOfBirth.js

@@ -0,0 +1,2 @@
+const cityOfBirth = "Bolton"
+console.log(`I was born in ${cityOfBirth}`)

percentage-change.js

@@ -0,0 +1,10 @@
+let carPrice = "10,000";
+let priceAfterOneYear = "8,543";
+
+carPrice = Number(carPrice.replaceAll(",", ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+
+const priceDifference = carPrice - priceAfterOneYear;
+const percentageChange = (priceDifference / carPrice) * 100;
+
+console.log(`The percentage change is ${percentageChange}`);

randomNumber.js

@@ -0,0 +1,5 @@
+const minimum = 20;
+const maximum = 50;
+
+const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+console.log(num)

timeFormat.js

@@ -0,0 +1,10 @@
+const movieLength = 1000000000000000000000; // length of movie in seconds
+
+const remainingSeconds = movieLength % 60;
+const totalMinutes = (movieLength - remainingSeconds) / 60;
+
+const remainingMinutes = totalMinutes % 60;
+const totalHours = (totalMinutes - remainingMinutes) / 60;
+
+const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
+console.log(result);