London | 26-ITP-May | Russom Gebremeskel | Sprint 1 | Coursework

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

@@ -4,3 +4,10 @@ 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
+
+// Answers 
+// Line 3 is updating the value of the variable count by adding 1 to its current value. 
+// The = operator is an assignment operator that takes the value on the right side 
+// (which is `count + 1`) and assigns it to the variable on the left side (`count`). 
+// This means that after line 3 is executed, the value of `count` will be incremented by 1.
+

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

@@ -5,7 +5,8 @@ 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];
+// String indexing is used to access the first character of each string. 
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 

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

@@ -13,11 +13,16 @@ const filePath = "/Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt";
 const lastSlashIndex = filePath.lastIndexOf("/");
 const base = filePath.slice(lastSlashIndex + 1);
 console.log(`The base part of ${filePath} is ${base}`);
+// The base part of /Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt is file.txt
 
 // 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); // Keeps everything except the last slash just before week-1/interpret.
+const ext = filePath.slice(lastSlashIndex + 1).split(".")[1]; // Keeps everything after the last slash and splits it into an array of strings at the dot.
+console.log(`The dir part of ${filePath} is ${dir}`); 
+console.log(`The ext part of ${filePath} is ${ext}`);
+// The dir part of /Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt is /Users/mitch/cyf/Module-JS1/week-1/interpret
+// The ext part of /Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt is txt
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn

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

@@ -2,8 +2,16 @@ const minimum = 1;
 const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+console.log(num);
 
 // 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
+
+// Answers
+// num represents a random integer between 1 and 100, inclusive.
+// Math.floor() rounds down to the nearest integer. 
+// Math.random() generates a random decimal number between 0 and 1 but not including 1.
+// maximum - minimum + 1 helps to keep both end of the range 1 to 100 after multiplying by Math.random()
+// + minimum shifts the range up to start at 1 instead of 0 

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

@@ -1,2 +1,5 @@
-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 forward slash and asterisk for multi-line or block comments as used above line 1 to 3. Or we can use double forward slashes for single line comments as used on this 5.

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;
-age = age + 1;
+//age = age + 1; The variable age is declared as a constant using the const keyword, which means its value cannot be changed after it is assigned. 
+const newAge = age + 1; // A new variable called newAge is assigned.This way, we can still calculate the new age without modifying the original constant variable.
+

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

@@ -2,4 +2,9 @@
 // what's the error ?
 
 console.log(`I was born in ${cityOfBirth}`);
+const cityOfBirth = "Bolton"; // The variable cityOfBirth is declared after it is used in the console.log statement.
+
+// The order of the code should be as below.
+
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -1,4 +1,4 @@
-const cardNumber = 4533787178994213;
+const cardNumber = "4533787178994213"; // parentises
 const last4Digits = cardNumber.slice(-4);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
@@ -7,3 +7,11 @@ const last4Digits = cardNumber.slice(-4);
 // 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
+
+// Answer
+// "TypeError: cardNumber.slice is not a function" is the error that it was given when running the code. 
+// This error occurs because the `slice` method is a string method, and `cardNumber` is a number, not a string. 
+// Therefore, we cannot use `slice` directly on a number.
+// To fix the issue, we need to convert `cardNumber` to a string by adding parentises.
+
+

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

@@ -1,2 +1,6 @@
 const 12HourClockTime = "8:53pm";
 const 24hourClockTime = "20:53";
+
+// In js variable names cannot start with a number. The variable names are changed to start with a letter instead of a number as below.
+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";

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;
@@ -20,3 +20,19 @@ 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?
+
+// Answer
+// a) Line 4: Number(carPrice.replaceAll(",", "")); and carPrice.replaceAll(",", "")
+// a) Line 5: Number(priceAfterOneYear.replaceAll("," "")); and priceAfterOneYear.replaceAll("," "")
+
+// b) The error is coming from line 5. The error is occurring in the replaceAll method a comma is missing between ("," "") it should be (",", "") to fix the problem.
+
+// c) line 4: carPrice = Number(carPrice.replaceAll(",", ""));
+// c) line 5: priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+
+// d) Line 1: let carPrice = "10,000";
+// d) Line 2: let priceAfterOneYear = "8,543";
+// d) Line 7: const priceDifference = carPrice - priceAfterOneYear;
+// d) Line 8: const percentageChange = (priceDifference / carPrice) * 100;
+
+// e) Number() is converting the string into a number. replaceAll() is removing the comma from the string.

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

@@ -23,3 +23,17 @@ console.log(result);
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// answer
+
+// a) 6 variables: movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours and result
+
+// b) 1 function calls: console.log(result)
+
+// c) Reminder operator: movieLength (8784 seconds)is divided by 60 and converted into minutes. The reminder value then stored as seconds.
+
+// d) It calculates how many full minutes (60 seconds) in movieLength are there excluding the seconds. 
+
+// e) total movie length in hours, minuets and seconds. movieDuration can be an alternative variable. 
+
+// f) I tried negative and decimal number. The code works but it doesn't make any sense to represent with this type of values other than integers.

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

@@ -25,3 +25,16 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// Answers
+// 1) variable const penceStringWithoutTrailingP stores the value of only the pennies part without the p. 
+// This is done first with penceString.length -1 removes the last index of pence string (p). 
+// Then penceString.substring(0) returns the characters from 0 to 2 of the indexes(399) 
+
+// 2) paddedPenceNumberString adds 0 at the beginning until the string is 3 characters long to penceStringWithoutTrailingP variable
+
+// 3) pounds stores 3 by first paddedPenceNumberString.length - 2 removing index 1 and 2. Then paddedPenceNumberString.substring(0) returning index 0.
+
+// 4) pence store the pennies first .length starting from index 1 then padEnd adding 0 to characters that less than 2 counts.
+
+// 5) console.log prints out the final result adding a £ sign at the beginning and a . between pounds and pence.

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

@@ -9,10 +9,16 @@ Let's try an example.
 
 In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
-
 What effect does calling the `alert` function have?
 
+- A window pops up with `"Hello world!"` message
+
 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?
+
+- a new window popup saying what is your name with a text input field for user to type.
+
 What is the return value of `prompt`?
+
+- A text string that input by the user is returned.

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

@@ -5,12 +5,20 @@ In this activity, we'll explore some additional concepts that you'll encounter i
 Open the Chrome devtools Console, type in `console.log` and then hit enter
 
 What output do you get?
+- ƒ 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 means display or print a message 
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+
+- console.log display data inside log. console.assert is evaluate if a condition is true. The `.` means telling console or any other function to access data inside that object just after the dot.