Brussels | ITP-2025-1 | Truong Vinh Kien | Week 5 | Sprint 2 all exercices

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

@@ -4,3 +4,9 @@ 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 try to increment the variable count by 1.
+ * after the = operator we use the current count variable (which is 0) and add 1 to it.
+ * then we reassign the result back to the count variable.
+ **/

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]}`;
 
-// https://www.google.com/search?q=get+first+character+of+string+mdn
+console.log(initials);
 
+// https://www.google.com/search?q=get+first+character+of+string+mdn

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

@@ -17,7 +17,10 @@ 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);
+console.log(`The dir part of ${filePath} is ${dir}`);
+const lastDotIndex = filePath.lastIndexOf(".");
+const ext = filePath.slice(lastDotIndex);
+console.log(`The ext part of ${filePath} is ${ext}`);
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn

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

@@ -7,3 +7,19 @@ 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
+
+/**
+ * The expression is generating a random integer between the minimum and maximum values.
+ * Math.floor() will round down the number to the nearest integer.
+ * Math.random() will generate a random number between 0 and 1 (not including 1).
+ * The expression (maximum - minimum + 1) calculates the range of possible values.
+ * Multiplying Math.random() by this range scales the random number to the desired range.
+ * Adding minimum shifts the range to start from the minimum value.
+ * Finally, Math.floor() ensures that the result is an integer.
+ **/
+console.log(num);
+//example output: 42
+//example output: 7
+//example output: 56
+//example output: 1
+//example output: 48

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

@@ -1,2 +1,6 @@
 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?
+
+//this error occur because these are plain text not code
+//we can turn them into comment by adding // at the beginning of each line
+//or we can put them inside /* and */ to turn them into block comment

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

@@ -2,3 +2,8 @@
 
 const age = 33;
 age = age + 1;
+
+// this error occur because we are trying to reassign a value to a constant variable
+// to solve this problem we can change the const to let
+// let age = 33;
+// age = age + 1;

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

@@ -3,3 +3,8 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// this error occur because we are trying to use the variable cityOfBirth before it is declared
+// to solve this problem we can move the declaration of cityOfBirth before the console.log line
+// const cityOfBirth = "Bolton";
+// console.log(`I was born in ${cityOfBirth}`);

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

@@ -7,3 +7,9 @@ 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
+
+// This error occur because we are trying to use the method slice on a number
+// To solve this problem we can convert the number to a string by using toString() method
+// const last4Digits = cardNumber.toString().slice(-4);
+// console.log(last4Digits);
+// example output: 4213

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

@@ -1,2 +1,7 @@
 const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const 24hourClockTime = "08:53";
+
+// This error occur because variable names cannot start with a number
+// To solve this problem we can rename the variables to start with a letter
+// const hour12ClockTime = "20:53";
+// const hour24ClockTime = "08:53";

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

@@ -12,11 +12,40 @@ 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
+/* 
+    4 functions calls in line 4 and line 5
+    Line 4: carPrice.replaceAll(",", "")
+    Line 4: Number(carPrice.replaceAll(",", ""))
+    Line 5: priceAfterOneYear.replaceAll("," "")
+    Line 5: Number(priceAfterOneYear.replaceAll("," ""))
+*/
 
 // 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
+    this error occur because it miss a comma in the expression priceAfterOneYear.replaceAll("," "")
+    to solve this problem we can add a comma between the two quotation marks
+    priceAfterOneYear.replaceAll(",", "")
+*/
 
 // c) Identify all the lines that are variable reassignment statements
+/*
+    2 variable reassignment statements in line 4 and line 5
+    Line 4: carPrice = Number(carPrice.replaceAll(",", ""));
+    Line 5: priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+*/
 
 // d) Identify all the lines that are variable declarations
+/*
+    4 variable declarations in line 1, 2, 7 and 8
+    Line 1: let carPrice = "10,000";
+    Line 2: let priceAfterOneYear = "8,543";
+    Line 7: const priceDifference = carPrice - priceAfterOneYear;
+    Line 8: const percentageChange = (priceDifference / carPrice) * 100;
+*/
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+/*
+    this expression is converting the string carPrice to a number
+    it will return NaN if the string cannot be converted to a number
+*/

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

@@ -12,14 +12,47 @@ 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?
+/*
+    6 variable declarations in line 1, 3, 4, 6, 7 and 9
+    Line 1: const movieLength = 8784; // length of movie in seconds
+    Line 3: const remainingSeconds = movieLength % 60;
+    Line 4: const totalMinutes = (movieLength - remainingSeconds) / 60;
+    Line 6: const remainingMinutes = totalMinutes % 60;
+    Line 7: const totalHours = (totalMinutes - remainingMinutes) / 60;
+    Line 9: const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;
+*/
 
 // b) How many function calls are there?
+/*
+    1 function calls console.log() 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
+/*
+    The expression movieLength % 60 is using the modulus operator (%).
+    This operator returns the remainder of a division operation.
+    In this case, it divides movieLength (which is 8784) by 60.
+    MovieLength % 60 gives us the remaining seconds after divided by 60.
+*/
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+/*
+    The expression (movieLength - remainingSeconds) / 60 is calculating the total number of whole minutes in the movie length.
+    First, it subtracts the remaining seconds (calculated in line 3) from the total movie length in seconds (movieLength).
+    This gives the total number of seconds that can be fully converted into minutes.
+    Then, it divides that result by 60 (the number of seconds in a minute) to convert those seconds into minutes.
+    The final result is assigned to the variable totalMinutes, which represents the total number of whole minutes in the movie length.
+*/
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
-
+/*
+    The variable result represents the duration of the movie.
+    A better name for this variable could be movieDuration.
+*/
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+/*
+    This code will work for all positive integer values of movieLength.
+    It will correctly calculate the hours, minutes, and seconds for any length of movie given in seconds.
+    However, if movieLength is a negative number or a non-integer (like a decimal), the code may not produce meaningful results.
+*/

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

@@ -25,3 +25,11 @@ 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):  extract the whole string except the last character from the penceString variable and assign to a new variable penceStringWithoutTrailingP
+  3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"): ensures that the string has at least 3 characters by adding with leading zeros if necessary
+  4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2): extracts the whole string except the last two characters
+  5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0"): extracts the last 2 characters and ensure it has two digits by adding with zeros after the remaining character if necessary
+  6. console.log(`£${pounds}.${pence}`): outputs the final formatted price in pounds and pence to the console
+*/

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?
+it call a pop up with your message and an 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?
+It will call a pop dialog with a message and an input field. It has a ok and cancel button as well.
 What is the return value of `prompt`?
+It returns the value of what was wrote on the input field.

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

@@ -7,10 +7,12 @@ Open the Chrome devtools Console, type in `console.log` and then hit enter
 What output do you get?
 
 Now enter just `console` in the Console, what output do you get back?
-
+ƒ log() { [native code] } it's a function
 Try also entering `typeof console`
-
+'object'
 Answer the following questions:
 
-What does `console` store?
+What does `console` store? console store an object that contain some functions.
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+the syntax 'console.log' or 'console.assert' means u re trying to access a function of the console object.
+the dot is used to access the function of an object

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

@@ -1,6 +1,8 @@
 // Predict and explain first...
 //  =============> write your prediction here
-
+/*
+    My prediction is that this code will produce an error because there is a variable name conflict.
+*/
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
@@ -10,4 +12,18 @@ function capitalise(str) {
 }
 
 // =============> write your explanation here
+/*
+    The error is occurring because there is a variable name conflict.
+    Inside the function capitalise, there is a parameter named str and a variable declared with let also named str.
+    This causes a syntax error because we cannot declare two variables with the same name in the same scope.
+    To fix this problem, we can rename the variable declared with let to a different name.
+*/
+
 // =============> write your new code here
+
+function capitalise(str) {
+  let capitalisedStr = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return capitalisedStr;
+}
+
+console.log(capitalise("hello")); // example output: "Hello"

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

@@ -2,6 +2,10 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+/*
+    My prediction is that this code will produce an error because there is a variable name conflict.
+    and the console.log statement is trying to access decimalNumber which is not defined in that scope.
+*/
 
 // Try playing computer with the example to work out what is going on
 
@@ -15,6 +19,20 @@ function convertToPercentage(decimalNumber) {
 console.log(decimalNumber);
 
 // =============> write your explanation here
-
+/*
+    The error is occurring because there is a variable name conflict.
+    Inside the function convertToPercentage, there is a parameter named decimalNumber and a variable declared with const also named decimalNumber.
+    This causes a syntax error because we cannot declare two variables with the same name in the same scope.
+    To fix this problem, we can rename the variable declared with const to a different name.
+    and also, the console.log statement is trying to access decimalNumber which is not defined in that scope.
+*/
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+
+function convertToPercentage(decimalNumber) {
+  const percentageValue = decimalNumber;
+  const percentage = `${percentageValue * 100}%`;
+
+  return percentage;
+}
+console.log(convertToPercentage(0.75));

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

@@ -1,20 +1,34 @@
 
 // Predict and explain first BEFORE you run any code...
 
+
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+/*
+    My prediction is that this code will produce an error because the parameter name is not a valid identifier.
+*/
 
 function square(3) {
     return num * num;
 }
 
 // =============> write the error message here
-
+/*
+    SyntaxError: Unexpected number
+*/  
 // =============> explain this error message here
-
+/*
+    The error is occurring because the parameter name "3" is not a valid identifier in JavaScript.
+    In JavaScript, parameter names must start with a letter, underscore (_), or dollar sign ($) and cannot be a number.
+    To fix this problem, we can rename the parameter to a valid identifier, such as "num".
+*/
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
 
+function square(num) {
+    return num * num;
+}
 
+console.log(square(4)); 

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

@@ -1,14 +1,27 @@
 // Predict and explain first...
 
 // =============> write your prediction here
-
+/*
+    My prediction is that this code will produce an error because the function multiply does not return any value.
+*/
 function multiply(a, b) {
   console.log(a * b);
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
 // =============> write your explanation here
-
+/*
+    The error is occurring because the function multiply does not return any value.
+    When we call multiply(10, 32), it calculates the product but it does not return the result.
+    Therefore, when we try to use the return value of multiply in the console, it results in undefined.
+    To fix this problem, we need to add a return statement in the multiply function to return the product of a and b.
+*/
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+
+function multiply(a, b) {
+  return a * b;
+}
+
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`); // example output: The result of multiplying 10 and 32 is 320

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

@@ -1,5 +1,8 @@
 // Predict and explain first...
 //  =============> write your prediction here
+/*
+    My prediction is that this code will produce an error because the function sum does not return any value.
+*/
 
 function sum(a, b) {
   return;
@@ -9,5 +12,16 @@ function sum(a, b) {
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+/*
+    The error is occurring because the function sum does not return the expected sum of a and b.
+    The return statement is currently returning undefined because there is no expression after the return keyword.
+    To fix this problem, we need to modify the return statement to return the result of a + b.
+*/
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+
+function sum(a, b) {
+  return a + b;
+}
+
+console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);