London | 26-ITP-Sep | Rawan Almutairi | Sprint 2 | JavaScript exercises

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

@@ -4,3 +4,4 @@ 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
+//a variable is initialised and assigned a value zero, than it was reassigned additing 1 to its value.

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

@@ -5,6 +5,10 @@ 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 = ``;
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
+
+const initials = `${firstName[0]}${middleName[0]}${lastName[0]}`;
+
+console.log(initials); // Output CKJ

Sprint-2/1-key-exercises/3-paths.js

@@ -9,15 +9,52 @@
 
 // (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);
+//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
+
+// from here start my explaination of the code I see for education purposes.
+// this is a file system that allows users to manipulate what files they see and what information they omit, and they use string 
+//methods to do that 
+// most common methods developers use to manipulate the files are included in this file Sprint-2\1-key-exercises\manipulating files.txt
+
+//  in this example the string methods are used to manipulate the file system
+
 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}`);
+// a variable is created to store the file path of a file in the file system
+//const lastSlashIndex = filePath.lastIndexOf("/");
+// a variable is created and identified to find the last occurance of the "/" character in the filePath variable, which is used to separate directories and files in a file system
+//const base = filePath.slice(lastSlashIndex + 1);
+// a variable is created and identified to extract the base part of the filePath variable, which is the name of the file and its extension, by using the slice method 
+//console.log(`The base part of ${filePath} is ${base}`);
+// console.log is used to print the base part of the filePath variable to the console, which is the name of the file and its extension
 
 // 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 lastSlashIndex = filePath.lastIndexOf("/");
+// here we have the variable lastslashIndex already created and identified its position
+// stores the position or (index) of "/" in filePath, so this "/" is used as a symbol that storers the number index or a place that seprate dir from base 
+const dir = filePath.slice(0, lastSlashIndex);
+console.log(dir);
+// we show our result in the console
+const lastDotIndex = filePath.lastIndexOf('.');
+// we create a variable and assign its value using the indexOf to be from the dot location
+const ext = filePath.slice(lastDotIndex);
+// we create a variable where we assign its value using the slice method to be from the dot only
 
-// https://www.google.com/search?q=slice+mdn
+console.log(ext)
+// we print our result in the console
+//slice(startIndex, endIndex)
+// means, start here and stop here. we are doing this to seprate the dir from base so we need to tell it where to start and where to end, hence that is why we use slice method,
+// my comments needs correcting to look profissional -_-

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

@@ -7,3 +7,16 @@ 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
+
+
+//here starts my learning 
+
+// first const minimun, const maximum are the variables 
+// = the assignmen operator
+// what comes after = is what the variable will store 
+// Math.floor is a method and here we are telling it that its argument is to use the random method 
+// and multiply the result before rounding with the maximum and minimum variables we created 
+// * is a multiplication operator 
+// to understand what is going on we need to understand what the floor and random methods do
+//Math.floor (rounds down to the nearest whole number) and than pass it to Math.floor
+// we are asking the program to round whatever result we have to the nearest whole number

Sprint-2/2-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 use slash to comment it. So the computer doesn't excute the text.

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

@@ -1,4 +1,9 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+
+//we change the variable declaration and reassign its value
+// variable declaration keywords 
+// const can't be used to reassign a value 
+// let can be used to reassign a value 

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

@@ -3,3 +3,5 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// the variable was declared after the print function so the program doesn't know what is cityofBirth. Therefore it can't perform the print function or excuted before declaring the variable 

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

@@ -7,3 +7,4 @@ 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
+// in this case its a reference error the program is trying to access a value that wasn't declared. In this case a variable.

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";
+// an identifier or keyword can't follow a numeric literal. We fix this by writing the numbers in words format
+
+//const 12HourClockTime = "8:53pm";
+//const 24hourClockTime = "20:53";

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;
@@ -11,12 +11,16 @@ 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
 
+// a) How many function calls are there in this file? Write down all the lines where a function call is made
+//5 FUNCTION calls. Line 4, 5, 10.
 // 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, column 61. Thhere is nothing seprating the two indexes. A comma can be used to seprate them.
 // c) Identify all the lines that are variable reassignment statements
-
+//Two lines 4 and 5
 // d) Identify all the lines that are variable declarations
-
+//four lines 1,2,7,8
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+//The replace.all method is used to include the car price and the price after one year of depreciation.
+ //The purpose of the expression is to take the price string and search for every comma and replace it
+ // we are saying replace this "," , with this "" and because of the empty string it means without a comma.

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

@@ -11,15 +11,17 @@ 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?
-
+// a) How many variable declarations are there in this program? 
+// 6 declarations
 // b) How many function calls are there?
-
+// 1 function call in line 10
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
-
+// "operator returns the remainder left over when one operand is divided by a second operand. It always takes the sign of the dividend."
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
-
+// it means the number of minutes in a film is calculated by calculating the number of seconds in the film
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
-
+//the variable result represesnt the length of the film in hours,minutes,and seconds. A better name would be movie time.
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+//  However, it doesn't work when the leading number of a decimal is zero like this 08784 because it interpreted as octal literal and 8 can't work in octal numeration 
+//"The octal number system is a base-8 math and computing system that uses only eight digits: 0, 1, 2, 3, 4, 5, 6, and 7"

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

@@ -25,3 +25,33 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 2. const penceStringWithoutTrailingP  = penceString.substring(
+ // 0,
+ // penceString.length - 1
+//);
+//INITIALISES A STRING VARIABLE AND ASSIGN ITS VALUE USEING THE penceString.substring
+// so what happins is penceString.substring is using the value from the application or calculation of (
+  //0,
+ // penceString.length - 1
+//);
+// we are tillING IT TO start from the first inex (0) and not to include index 3 which penceString.length than use the operator - to subtract 1
+// we intialise a string variable const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"); and assign its value to be
+//const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//const pounds = paddedPenceNumberString.substring(
+ // 0,
+  //paddedPenceNumberString.length - 2
+//);
+// we assign the value to be starting with  MINUMUM LENGTH IS 3 CHARACTERS than if not ADD THE VALUE 0 TO THE BEGINNING
+// we initialise a variable const pounds and assign its value to be the value from using paddedPenceNumberString.substring
+//paddedPenceNumberString.substring value is found by starting from the first index WITH LENGTH 3 and ending with paddedPenceNumberString.length subtracted by the operator 2
+
+// IN THIS LINE const pence = paddedPenceNumberString
+const pence = paddedPenceNumberString
+  .substring(paddedPenceNumberString.length - 2)
+  .padEnd(2, "0");
+
+console.log(`£${pounds}.${pence}`);
+// we initialise a string variable and assign its value to be the paddedPenceNumberString variable with the value from using the substring method
+// the substring method is calculated by using the length property or the value of paddedPenceNumberString subtracting it by 2 using operator -
+// than using the method .padEnd to specify that if the length is not two add the value 0
+// last we ask the console to print the values in pounds and pence