Manchester | 26-ITP-Sep | Aklilu Mihtsun | Sprint 2 | Complete Sprint 2 Coursework

Sprint-2/1-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
+
+// Line 3 is updating the count variable by reassigning new value that is count + 1 or (0 + 1 which is 1)
+// The = operator is assigning the count variable we declared in line 1 with new value

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

@@ -5,6 +5,8 @@ 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 = `${firstName.charAt(0)}${middleName.charAt(0)}${lastName.charAt(0)}`;
+
+//console.log(initials);
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn

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

@@ -12,12 +12,15 @@
 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}`);
+const lastDotIndex = base.lastIndexOf(".");
+//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);
+const ext = base.slice(lastDotIndex);
+//console.log(dir);
+//console.log(ext);
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn

Sprint-2/1-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);
+
 // 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
+
+// num is a variable declared to hold (being assigned) the value of the calculated result of the var minimum,
+// var maximum , the Math.random() method and Math.floor() method
+// This expression can be broken down in to the following main steps
+// 1. the inner parentheses (maximum - minimum + 1) is calculated because that is the inner most expression
+// 2. then the Math.random() generates random number which is greater than or equal to 0 but less than 1  and multiply with the result of (maximum - minimum + 1)
+// 3. then the Math.floor() rounds down the result of (Math.random() * (maximum - minimum + 1)) to the nearest whole number
+// 4. finally the minimum is being added to the down rounded whole number and the variable num holds the value
+// after running the program the value of num looks like this 51,8,85,8,99,21 random numbers that are greater than or equal to 1 but less than 100
+
+// the expression maximum - minimum + 1 determines how many possible whole numbers can the random method generate
+// and it affects the range by stretching it out to be exactly as wide as the total count of numbers we need.
+// the + minimum at the end makes the starting point for our random numbers to be the value of the minimum instead of 0

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

@@ -1,2 +1,9 @@
-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?
+
+//OR
+
+/* 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 put the 2 lines in comment by adding // before each single line or we can enclose them in /* */ if we want to comment multi-line

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

@@ -1,4 +1,12 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+//const age = 33;
+let age = 33;
 age = age + 1;
+console.log(age);
+
+/* When we try to run the code it is giving us an error message saying TypeError: Assignment to constant variable, 
+this error is telling us that we are trying to perform an operation on a value that is not the correct type, 
+in our case reassigning a cons variable. The cons keyword prevents us from reassigning a variable
+We can overcome the error by changing the declaration keyword to "let"
+*/

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

@@ -1,5 +1,11 @@
 // 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}`);
+//const cityOfBirth = "Bolton";
+
+/* When we try to run our code it is giving us an error saying ReferenceError: Cannot access 'cityOfBirth' before initialization
+and this is because we tried to access the var cityOfBirth before we declared and initialized it*/
+
+// We can overcome this error by declaring and initializing the var cityOfBirth before accessing it

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

@@ -1,9 +1,16 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+//const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);
 
 // 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
+
+// I am predicting the code wont't work because the slice method does not work for numbers I guess
+// when i run the program it is giving an error saying "TypeError: cardNumber.slice is not a function"
+// It is giving this error because our var cardNumber is number and numbers don't have slice() method & it is what I predicted
+// In order our code to be able to run we need first to change the number type into String so that the slice() method can function

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

@@ -1,2 +1,13 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+//const 12HourClockTime = "8:53pm";
+//const 24hourClockTime = "20:53";
+
+const HourClockTime12 = "8:53pm";
+const hourClockTime24 = "20:53";
+
+console.log(HourClockTime12);
+console.log(hourClockTime24);
+
+// when we tried to run the code it threw an error saying "SyntaxError: Invalid or unexpected token"
+// this happened because when we were declaring a variable we gave an invalid name to the identifier which started with number
+// variable name must start with letters or _ or $
+// we can fix it buy removing the front number of the identifiers and may be put them last

Sprint-2/3-mandatory-interpret/1-percentage-change.js

@@ -2,7 +2,8 @@ let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+//priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -20,3 +21,23 @@ 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) In this file we can say we have 5 function calls (2 function calls & 3 method calls to be specific) and they are in line 4, 5 and 10
+
+// b) When we run the code the error is generating from line 5 and the reason is that when we pass more than 1 argument
+// in a method we need to separate them with comma, but in line 5 there is no comma to separate the arguments
+// we can fix it by adding a comma to separate the arguments
+
+// c) Lines 4 and 5 are reassignment statements
+
+// d) Lines 1, 2, 7 and 8 are variable declarations
+
+// e) The expression Number(carPrice.replaceAll(",",""))
+// 1. carPrice.replaceAll(",","") this method is removing the "," from the String variable carPrice by replacing the "," with empty String which is ""
+// all left then is just the String digits without ","
+// 2. Number("String digit without comma") and this function converts the String digit to number digit
+// and finally  Number(carPrice.replaceAll(",","")) expression gives us number
+
+// the purpose of Number(carPrice.replaceAll(",","")) is to convert the carPrice string with commas into a clean, usable number so we can perform mathematical calculations on it

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

@@ -23,3 +23,20 @@ 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) In the above code there are 6 variable declarations
+
+// b) There is only 1 function call in the code
+
+// c) the expression movieLength % 60 is trying to divide the movieLength by 60 then get the remainder
+
+// d) totalMinutes = (movieLength - remainingSeconds) / 60 in this expression
+// 1. (movieLength - remainingSeconds) the values  inside the parenthesis is calculated first then it is divided by 60
+//  then the value of expression is assigned to the var totalMinutes
+// so the expression simply means that we are trying to convert the movie length in seconds into full minutes by removing the remaining seconds
+
+// e) the variable result represents the formatted time in hours:minutes:seconds. I would rename it time
+
+// f) it will not work with negative numbers because we can not have negative time

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

@@ -2,13 +2,13 @@ const penceString = "399p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
-  penceString.length - 1
+  penceString.length - 1,
 );
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
 const pounds = paddedPenceNumberString.substring(
   0,
-  paddedPenceNumberString.length - 2
+  paddedPenceNumberString.length - 2,
 );
 
 const pence = paddedPenceNumberString
@@ -25,3 +25,47 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// 2. From line 3 to line 6 const penceStringWithoutTrailingP is declared and it will hold the value of
+// penceString.substring(0, penceString.length - 1)
+// which is "399". We got this value by the method substring(0, penceString.length - 1) called by penceString
+// Breaking down the expression penceString.substring(0, penceString.length - 1)
+// a) penceString.length - 1 this counts the number of characters in the penceString String and then subtracts 1 from it (4-1=3)
+// then it will look like this penceString.substring(0, 3)
+// b) penceString.substring(0, penceString.length - 1) then the substring method called by penceString
+// is used produce a slice of small string from a big string
+// it takes two arguments the first one tells where to start slicing and the second one tells where to stop
+// (but the last character is not included)
+// Therefore const penceStringWithoutTrailingP will be assigned "399"
+
+// 3. In line 8 const paddedPenceNumberString is declared and it will hold the value of penceStringWithoutTrailingP.padStart(3, "0")
+// which is still "399". In this expression we used the method padStart called by penceStringWithoutTrailingP and this method is basically
+// adds characters at the start of our String. It takes two arguments the first one is telling how many characters we want in our String
+// and second argument tells the character that needs to be added so that we get out desired number of characters in our String.
+// since our String length is 3 the method will not do anything
+
+// 4. From line 9 to line 12 const pounds is declared and it will hold the value of paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2,)
+// which is "3". We got this value by the method substring(0, paddedPenceNumberString.length - 2,) called by paddedPenceNumberString
+// Breaking down the expression paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2,)
+// a) paddedPenceNumberString.length - 2 this counts the number of characters in the paddedPenceNumberString then subtracts 2 from it (3-2=1)
+// then it will look like this paddedPenceNumberString.substring(0, 1)
+// b) paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2,) then the substring method called by paddedPenceNumberString is used to
+// produce a slice of small string from a big string
+// it takes two arguments the first one tells where to start slicing and the second one tells where to stop
+// (but the last character is not included)
+// Therefore const pounds will assigned "3"
+
+// 5. From line 14 to line 16 const pence is declared and it will hold the value of
+// paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0") which is "99"
+// Breaking down the expression
+// a) paddedPenceNumberString.length - 2 this will count the number of characters in paddedPenceNumberString and then subtracts 2 from it (3-2=1)
+// paddedPenceNumberString.substring(paddedPenceNumberString.length - 2) then this substring method will produce small string from it starting from index 1 which will be "99"
+//then finally paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0") the padEnd method will add characters at the end of the String
+// and  will take two arguments first will tell how many characters we need in our string and the second will tell the character that needs to be added
+// since our String length is 2 the method will do nothing
+
+// 6. Finally line 18 will print out the desired format we have added what to be printed inside the back-ticks if they are variables we will put them in ${}
+
+// note on line 5 and line 11
+// "," was simply added at the end of the second argument just to tell that we have finished listing our arguments
+// it does not mean we are going to put third argument. It can be ignored also it does not make a difference

Sprint-2/4-stretch-explore/chrome.md

@@ -1,15 +1,20 @@
-Open a new window in Chrome, right click an empty space on the page, select **Inspect** from the dropdown, then locate the **Console** tab.
+Open a new window in Chrome, right click page, select **Inspect** from the dropdown, then locate the **Console** tab.
 
 Voila! You now have access to the [Chrome V8 Engine](https://www.cloudflare.com/en-gb/learning/serverless/glossary/what-is-chrome-v8/).
 Just like the Node REPL, you can input JavaScript code into the Console tab and the V8 engine will execute it.
 
 Let's try an example.
 
-In the Chrome console, invoke the function `alert` with one argument, the string `"Hello world!"`;
+Click an empty space on tn the Chrome console, invoke the function `alert` with one argument, the string `"Hello world!"`;
 
 What effect does calling the `alert` function have?
 
+// The `alert` function displays a message to the user and it stops js execution until the user dismisses the alert
+
 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?
 What is the return value of `prompt`?
+
+// The `prompt` function opens a popup dialog and waits an input from a user. it stops js execution until the user inputs or cancel the popup dialog
+// The return value of `prompt` is a string

Sprint-2/4-stretch-explore/objects.md

@@ -13,4 +13,9 @@ Try also entering `typeof console`
 Answer the following questions:
 
 What does `console` store?
+
+// `console` stores methods
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+
+// The `console.log` or `console.assert` means access log or assert method from console object and the `.` is called the dot operator, and it is used to access the property or method of an object or value