Sheffield | 26-Jan-ITP | Daniel Aderibigbe | Sprint 1 | coursework/sprint-1

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
+
+//The right-hand side count + 1 is evaluated first to produce the value 1, then = assigns that results to count and overwrites the previous value of 0.
+// The one-term  word for this is increment. Because we are adding 1 to the count variable.

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

@@ -10,14 +10,16 @@
 // (All spaces in the "" line should be ignored. They are purely for formatting.)
 
 const filePath = "/Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt";
-const lastSlashIndex = filePath.lastIndexOf("/");
-const base = filePath.slice(lastSlashIndex + 1);
+const lastSlashIndex = filePath.lastIndexOf("/"); // 44
+const base = filePath.slice(lastSlashIndex + 1); // "file.txt"
 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);
 
-// https://www.google.com/search?q=slice+mdn
+const lastDotIndex = base.lastIndexOf(".");
+const ext = base.slice(lastDotIndex + 1);
+
+// https://www.google.com/search?q=slice+mdn

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

@@ -2,3 +2,5 @@
 
 const age = 33;
 age = age + 1;
+
+// The code will throw an error because age is declared as a const, which means it cannot be reassigned after its initial assignment. To fix this, age should be declared using let instead of const.

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}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+
+// The error is that the variable cityOfBirth is being used before it is declared and assigned a value. To fix this, the declaration should be before the console.log statement.

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
+
+//Initially, the code will not work because slice is a method that exist on strings and arrays. While the cardNumber is a number, so it will throw an error when trying to slice it
+
+//To fix this, we can convert the cardNumber to a string using the toString() method before applying 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";
+
+// A variable name cannot start with a number.

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 +13,26 @@ 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 in this file.
+// Line 4 : Number() and replaceAll()
+// Line 5 : Number() and replaceAll()
+// Line 10 : console.log()
+
 // 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?
 
+//// In the original version, the error came from line 5 because the replaceAll call was not written correctly (the arguments weren’t separated properly),
+// So JavaScript couldn’t parse it.
+// Fix: pass two valid string arguments to replaceAll, e.g. replaceAll(",", "") so commas are removed before converting to a number.
+
 // c) Identify all the lines that are variable reassignment statements
 
+// Line 4 and Line 5
+
 // d) Identify all the lines that are variable declarations
 
+// Line 1, 2, 7, 8.
+
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+// The expression is first calling the replaceAll method on the carPrice string to remove all commas. "10,000" ==> "10000"
+// Then it converts the resulting string into a number using the Number() function. "10000" ==> 10000

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

@@ -1,10 +1,10 @@
 const movieLength = 8784; // length of movie in seconds
 
 const remainingSeconds = movieLength % 60;
-const totalMinutes = (movieLength - remainingSeconds) / 60;
+const totalMinutes = (movieLength - remainingSeconds) / 60; //146
 
-const remainingMinutes = totalMinutes % 60;
-const totalHours = (totalMinutes - remainingMinutes) / 60;
+const remainingMinutes = totalMinutes % 60; //26
+const totalHours = (totalMinutes - remainingMinutes) / 60; // 0
 
 const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
 console.log(result);
@@ -13,13 +13,28 @@ console.log(result);
 
 // a) How many variable declarations are there in this program?
 
+// There are 6 Variable declarations.
+
 // b) How many function calls are there?
 
+// There are 2 function calls. Console.log().
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
+// movieLength % 60 gives the leftover seconds after converting seconds into whole minutes.
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+//It gets the total minutes by removing the leftover seconds and converting the remaining seconds into minutes by dividing by 60.
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+//remainingMinutes is the minutes part in an hours:minutes:seconds display
+// It can be named as minutesDisplay.
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// The code will work for all positive integer values of MovieLength.
+// If movieLength is negative, the code will still run but it will give a negative time which doesn't make sense in this context.
+// If movieLength is not an integer, it will still run but it may give unexpected results due to the way the modulus operator works with non-integer values.

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

@@ -1,27 +1,34 @@
 const penceString = "399p";
 
+// This creates a string variable that represents a price in pence, with the letter p at the end.
+
 const penceStringWithoutTrailingP = penceString.substring(
   0,
   penceString.length - 1
 );
 
+// This takes the string from the start up to (but not including) the last character, so it removes the trailing "p" and leaves "399"
+
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+// This makes sure the pence number has at least 3 characters by adding zeros to the front if it’s too short (so "5" would become "005"), and "399" stays "399".
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
 
+// This takes everything except the last 2 digits, which gives the pounds part (for "399" it becomes "3").
+
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
 
-console.log(`£${pounds}.${pence}`);
+//This takes the last 2 digits to get the pence part (for "399" it becomes "99") and ensures it is always 2 digits long by padding with zeros on the right if needed.
 
-// This program takes a string representing a price in pence
-// The program then builds up a string representing the price in pounds
+//.padEnd(2, "0") is unnecessary here because paddedPenceNumberString is always at least length 3 due to padStart(3, "0"), so substring(length - 2) will always return exactly two characters. That means the pence part is already guaranteed to be 2 digits.
+
+console.log(`£${pounds}.${pence}`);
 
-// You need to do a step-by-step breakdown of each line in this program
-// Try and describe the purpose / rationale behind each step
+// This prints the final formatted price by inserting pounds and pence into a template string, producing £3.99.
 
-// To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// This program takes a string representing a price in pence

Sprint-1/4-stretch-explore/chrome.md

@@ -12,7 +12,14 @@ invoke the function `alert` with an input string of `"Hello world!"`;
 
 What effect does calling the `alert` function have?
 
+- It opens an alert saying "Hello World!"
+
 Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`.
 
 What effect does calling the `prompt` function have?
+
+- It opens a prompt asking for an input
+
 What is the return value of `prompt`?
+
+- prompt returns the text the user type as a string (or null if they clicked cancel)

Sprint-1/4-stretch-explore/objects.md

@@ -6,11 +6,24 @@ Open the Chrome devtools Console, type in `console.log` and then hit enter
 
 What output do you get?
 
+- I am getting a function log() { [native code] }
+
 Now enter just `console` in the Console, what output do you get back?
 
+- console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …}
+
 Try also entering `typeof console`
 
+- Object
+
 Answer the following questions:
 
 What does `console` store?
+
+- `console` is an object that contains methods like log, errors, warn, info, and debug. etc.
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+
+- 'console.log' :Accesses the log function on the console object so you can print output.
+- 'console.assert' : Accesses the assert function on the console objects so you can report an error when the condition is false.
+- '.': Dot notation is used to access a property or method on an object (e.g console.log gets log from console).