London | 26-ITP-May | Dipa Sarker | Sprint 1 | Coursework

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

@@ -3,4 +3,6 @@ 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
+// The = sign means 'assignment' operator
+// In line 3, at first the calculation will be done at R.H.S, 
+// with the initial count value then the calculated value will be stored at the L.H.S count 

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

@@ -2,10 +2,5 @@ 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 = ``;
-
-// https://www.google.com/search?q=get+first+character+of+string+mdn
-
+let initials = `${firstName.charAt(0)}${middleName.charAt(0)}${lastName.charAt(0)}`;
+console.log(initials);

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

@@ -13,11 +13,6 @@ 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
+const dir = filePath.slice(0, lastSlashIndex);
+const dotIndex = base.lastIndexOf(".");
+const ext = base.slice(dotIndex);

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

@@ -2,8 +2,20 @@ 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?
+// num stores the result of the expression after calculating it.
 // 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
+// There is a range of numbers from 1 to 100. In the expression, 
+// (maximum - minimum + 1) calculates the size of the possible integers, which is 100. 
+// The Math.random() function generates a random decimal number in the range 0 ≤ x < 1.
+// This random decimal is then multiplied by the range size to scale it to a
+// value between 0 and 100. The result is a floating-point number in this interval.
+// Next, Math.floor() is used to round the number down to the largest integer less than
+// or equal to the calculated value, producing an integer between 0 and 99.
+// Finally, by adding minimum, the range is shifted from 0–99 to 1–100, giving a random
+// integer within the required range.
+// I have run 5 times the program and this produces different values each time because
+// Math.random() generates a new random decimal number every time. 
+// Since the final value of num depends on this function, the result changes on each execution.

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?
+We don't want the computer to run these 2 lines - how can we solve this problem?
+
+// We can solve this problem by writing those two lines as comments using //, 
+// because JavaScript ignores commented lines and they will not be executed by the computer.

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;
+
+// There is a constant variable age, which is fixed and it's value cannot be reassigned.
+// If we want to change the value of age, we have to use let instead of const.

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

@@ -3,3 +3,6 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// The variable const cityOfBirth = "Bolton"; needs to be declared at first. 
+// As it is not declared, JavaScript cannot find out the variable cityofBirth in console.log.

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

@@ -1,9 +1,19 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+console.log(cardNumber.toString());
+const cardNumber1 = cardNumber.toString()
+const last4Digits = cardNumber1.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
+// I think slice () works for strings or arrays not for numbers. That's why the code won't work.
 // Then run the code and see what error it gives.
+// After running code TypeError: cardNumber.slice is not a function this error shows.
 // 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
+// It gives this error because cardNumber doesn't have slice method. My prediction was beacuse 
+// cardNumber is number not string and the difference is that slice method called but it
+// doesn't exist on that type.
+// Then try updating the expression last4Digits is assigned to, in order to get the correct
+// value
+// Updated the expression in order to get in to the correct value.

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

@@ -1,2 +1,2 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+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;
@@ -12,11 +12,27 @@ 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
+// There are 5 function calls. carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// In the above 2 lines, 2 replaceAll() functions for carPrice and priceAfterOneyear and after executing them again Number() 
+// functions for the 2 variables.
+// At last, console.log() function for printing the executed value.
 
 // 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?
+// after running the code, the error is coming from this line priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));and
+// the error is  SyntaxError: missing ) after argument list. There is a comma missing in replaceAll() syntax. It should be
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));  
 
 // c) Identify all the lines that are variable reassignment statements
+// There are 2 variable reassignment statements. 
+// const priceDifference = carPrice - priceAfterOneYear;
+// const percentageChange = (priceDifference / carPrice) * 100;
 
 // d) Identify all the lines that are variable declarations
+// There are 4 variable declarations lines. 
+// let carPrice = "10,000";
+// let priceAfterOneYear = "8,543";
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// Firstly this expression replace all the commas from the variable carPrice = "10,000" to "10000" and then it converts 
+// string "10,000" to number 10000.

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

@@ -12,14 +12,23 @@ 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?
+// There are 6 variable declarations.
 
 // b) How many function calls are there?
+// There is one function call.
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// The expression movieLength % 60 devides the movieLength by 60 seconds and return the reminder 
+// which will be stroed in the const remainingSeconds.
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// Firstly, Removes the leftover seconds from movieLength and then converts the remaining seconds 
+// into whole minutes which will be stored into totalMinutes.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// The variable result reprents the movieLength in hours:minutes:seconds. The variable should be renamed by totalDuration.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// I have tried with 3 variables, 1515, 9999 & 70052. I observed that this code works succesfully with all the values
+// and gave me results for all the different movieLength in hours:minutes:seconds.

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

@@ -25,3 +25,18 @@ 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); : a variable declared and a function called
+// in the variable with substring method. In the substring method (penceString.length - 1) = 4 -1 = 3 then the function remains
+// penceString.substring(0, 3); from which we find const penceStringWithoutTrailingP = 399p.penceString.substring(0, 3); to 
+// const penceStringWithoutTrailingP = 399
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//    const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2); : another variable const paddedPenceNumberString 
+// declared and a function called in the variable with padStart method. penceStringWithoutTrailingP.padStart(3, "0"); will be 399.padStart(3, "0");
+// and finally const paddedPenceNumberString = "399". Secondly, another variable const pounds declared in which calculates the value in
+// pounds. For this, (0, paddedPenceNumberString.length - 2); will be (0, 1) and the const pounds = 399.substring(0, 1); calculates 
+// const pounds = 3
+// 4. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0"); : a variable pence declared
+// to calculate the value in pence. so, if we put the values it will be const pence = 399.substring(1).padEnd(2, "0"); which at first works for
+// substring and then for padEnd and will be const pence = 99;
+// 5. console.log(`£${pounds}.${pence}`); : this console function printed the prince in pounds and pence.And finally the printed output
+// will be £3.99

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

@@ -11,8 +11,11 @@ In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
 
 What effect does calling the `alert` function have?
+// `alert` function deisplays a popup dialogue box with a message and the user have to click 'ok' button. 
 
 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?
+// `prompt` function displays a dialogue box with a message and asks the the user to give input.
 What is the return value of `prompt`?
+//It returns the value which user inputs. In the question it is myName. 

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

@@ -5,12 +5,19 @@ 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] } . This is the output. The output indicates it is a function whose name is log() and which is built in
+//Javascript. 
 
 Now enter just `console` in the Console, what output do you get back?
+//console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …} . this is the output. In which console shows many functions it delt with such as debugging, error, info, log warn etc.
 
 Try also entering `typeof console`
+//The output is 'object'. Which means it is an object which perform many functions.
 
 Answer the following questions:
 
 What does `console` store?
+`console` stores different methods (functions). 
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+//Both are the function reference. If we further call `console.log` then the function runs and it will print output.
+console.assert() function writes an error message to the console if the assertion is false. If the assertion is true, nothing happens. `.` used to access the property of the object. In both the functions, `.` accesses `log` or `assert` property of the console object and get the values.