London | 25-ITP-May | Surafel Workneh | Data structure | Sprint 2 |

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

@@ -4,10 +4,25 @@
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
-function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
-}
+// function capitalise(str) {
+//   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+//   return str;
+// }
 
 // =============> write your explanation here
+// The function capitalize is trying to take a string input and return it with the first letter capitalized.
+// However, the error occurs because the variable 'str' is being declared twice: once as a parameter and again inside the function.
+// This is not allowed in JavaScript, as 'let' does not allow redeclaration of the same variable in the same scope.
+// This causes a syntax error because you cannot redeclare a variable with 'let' in the same scope.
 // =============> write your new code here
+
+function capitalise(str) {
+  let name = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return name;
+}
+capitalise("hello, check ");
+console.log(capitalise("hello, check "));
+// =============> write your explanation here
+// The function now uses a different variable name 'name' instead of 'str' inside the function.
+// This avoids the redeclaration error. The function takes a string input, capitalizes the first letter, and returns the modified string.
+// However, the return statement still returns 'str' instead of 'name', which is a mistake.

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

@@ -5,16 +5,35 @@
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
-  const percentage = `${decimalNumber * 100}%`;
-
-  return percentage;
-}
+// function convertToPercentage(decimalNumber) {
+// const decimalNumber = 0.5;
+// The above line will cause an error because 'decimalNumber' is being redeclared with 'const'
+// after it has already been defined as a parameter of the function.
+// This will result in a SyntaxError: Identifier 'decimalNumber' has already been declared.
+//  it is trying to declare a new constant variable with the same name as the parameter of the function: decimalNumber
+// const percentage = `${decimalNumber * 100}%`;
+// The above line correctly converts the decimal number to a percentage by multiplying it by 100
+// and appending a '%' sign.
+// However, the function will not execute due to the redeclaration error.
 
-console.log(decimalNumber);
+//   return percentage;
+// // }
 
+// console.log(decimalNumber);
+// console.log(decimalNumber) outside the function — but decimalNumber was only defined inside the function.
 // =============> write your explanation here
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+// =============> write your explanation here
+// The function now correctly takes a decimal number as input, converts it to a percentage by multiplying it by 100,
+// and returns the result as a string with a '%' sign appended. The redeclaration error has been fixed by removing the
+// unnecessary declaration of 'decimalNumber' inside the function. The function can now be called with a decimal number,
+// and it will return the corresponding percentage string.
+console.log(convertToPercentage(0.5)); // "50%"
+
+// The function now works correctly and returns the expected output without any errors.

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

@@ -1,20 +1,26 @@
-
 // Predict and explain first BEFORE you run any code...
-
+// the will be an error
 // this function should square any number but instead we're going to get an error
 
+// Why will an error occur when this program runs?
+//because the function parameter is incorrectly defined by real number instead of a variable name
+
 // =============> write your prediction of the error here
 
-function square(3) {
-    return num * num;
-}
+// function square(3) {
+//     return num * num;
+// }
 
 // =============> write the error message here
-
+//syntaxError: Unexpected number
 // =============> explain this error message here
-
+// The error occurs because the function parameter is defined as a number (3) instead of a variable name.
+// In JavaScript, function parameters must be variable names, not literal values. JavaScript is expecting a parameter name in the parentheses, not a value.
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
 
-
+function square(num) {
+  return num * num;
+}
+console.log(square(3)); // This will not work because 'num' is not defined outside the function

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

@@ -1,14 +1,30 @@
 // Predict and explain first...
 
+// The code below is intended to multiply two numbers and log the result.
+// However, it currently does not return the result correctly.
+// The function `multiply` is defined to take two parameters `a` and `b`.
+// It logs the product of `a` and `b` but does not return it.
+// The console.log statement outside the function attempts to log the result of calling `multiply(10, 32)`.
+// The expected output is "The result of multiplying 10 and 32 is 320".
+// However, since `multiply` does not return a value, the output will be "The result of multiplying 10 and 32 is undefined".
 // =============> write your prediction here
 
 function multiply(a, b) {
-  console.log(a * b);
+  // This function multiplies two numbers and logs the result
+  // but does not return it.
+  // It should return the product instead of just logging it.
+  // The current implementation will not return the product.
+  //console.log(a * b);
+  // This line should be changed to return the product
+  return a * b; // Corrected to return the product
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
-
 // =============> write your explanation here
+// // The code is intended to multiply two numbers and log the result.
+// However, it currently does not return the result correctly.
+// The expected output is "The result of multiplying 10 and 32 is 320".
+// The current output will be "The result of multiplying 10 and 32 is undefined".
 
 // Finally, correct the code to fix the problem
 //  =============> write your new code here

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

@@ -1,13 +1,20 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// The sum of 10 and 32 is undefined
 
-function sum(a, b) {
-  return;
-  a + b;
-}
+// function sum(a, b) {
+//   return;
+//   a + b;
+// }
 
-console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+// console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// The function called `sum` is defined to take two parameters `a` and `b`, but it does not return the result of adding them together.
+// Instead, it has a `return` statement which exits the function without returning any value.
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+function sum(a, b) {
+  return a + b;
+}
+console.log(sum(10, 32));

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

@@ -1,24 +1,37 @@
 // Predict and explain first...
+// This code is intended to find the last digit of a number, but it has a bug.
 
 // Predict the output of the following code:
+// Predict the output of the following code is '3' for the input 103. since the last digit of 103 is 3 and it is  a global variable, so regardless of the input, it will always return the last digit of the global variable `num` which is 103.
 // =============> Write your prediction here
 
-const num = 103;
+// const num = 103;
 
-function getLastDigit() {
-  return num.toString().slice(-1);
-}
+// function getLastDigit() {
+//   return num.toString().slice(-1);
+// }
 
-console.log(`The last digit of 42 is ${getLastDigit(42)}`);
-console.log(`The last digit of 105 is ${getLastDigit(105)}`);
-console.log(`The last digit of 806 is ${getLastDigit(806)}`);
+// console.log(`The last digit of 42 is ${getLastDigit(42)}`);
+// console.log(`The last digit of 105 is ${getLastDigit(105)}`);
+// console.log(`The last digit of 806 is ${getLastDigit(806)}`);
 
 // Now run the code and compare the output to your prediction
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
+
 // =============> write the output here
+// The output is always '3'
 // Explain why the output is the way it is
 // =============> write your explanation here
+// The output is always '3' because the function `getLastDigit` is using a global variable `num` which is set to 103
 // Finally, correct the code to fix the problem
 // =============> write your new code here
-
+function getLastDigit(num) {
+  return num.toString().slice(-1);
+}
+console.log(`The last digit of 42 is ${getLastDigit(42)}`);
+console.log(`The last digit of 105 is ${getLastDigit(105)}`);
+console.log(`The last digit of 806 is ${getLastDigit(806)}`);
 // This program should tell the user the last digit of each number.
 // Explain why getLastDigit is not working properly - correct the problem

Sprint-2/3-mandatory-implement/1-bmi.js

@@ -15,5 +15,15 @@
 // It should return their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
-    // return the BMI of someone based off their weight and height
-}
+  // return the BMI of someone based off their weight and height
+  // calculate the height squared
+  const heightSquared = height * height;
+  // calculate the BMI
+  const BMI = weight / heightSquared;
+  // return the BMI to 1 decimal place
+  return parseFloat(BMI.toFixed(1));
+}
+let weight = 70; // in kg
+let height = 1.73; // in meters
+
+console.log(`BMI is ${calculateBMI(weight, height)}`);

Sprint-2/3-mandatory-implement/2-cases.js

@@ -14,3 +14,38 @@
 // You will need to come up with an appropriate name for the function
 // Use the MDN string documentation to help you find a solution
 // This might help https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase
+
+function toUpperSnakeCase(string) {
+  // First convert the entire string to uppercase
+  const upperCaseString = string.toUpperCase();
+
+  // Then split it into words (assuming space-separated)
+  const wordsArray = upperCaseString.split(" ");
+
+  // Then join the array into a string using underscores
+  const result = wordsArray.join("_");
+  // Return the string in UPPER_SNAKE_CASE
+  return result;
+}
+// Example usage for this function
+// let string = "hello there";
+
+// console.log(`The string in UPPER_SNAKE_CASE is: ${toUpperSnakeCase(string)}`);
+
+console.log(
+  `The string in UPPER_SNAKE_CASE for 'hello there' is: ${toUpperSnakeCase(
+    "hello there"
+  )}`
+);
+
+console.log(
+  `The string in UPPER_SNAKE_CASE for 'lord of the rings' is: ${toUpperSnakeCase(
+    "lord of the rings"
+  )}`
+);
+
+console.log(
+  `The string in UPPER_SNAKE_CASE for 'example usage for this function' is: ${toUpperSnakeCase(
+    "example usage for this function"
+  )}`
+);

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

@@ -4,3 +4,32 @@
 // You will need to declare a function called toPounds with an appropriately named parameter.
 
 // You should call this function a number of times to check it works for different inputs
+function toPounds(penceString) {
+  // Remove the trailing "p" from the string
+  const penceStringWithoutTrailingP = penceString.substring(
+    0,
+    penceString.length - 1
+  );
+
+  // Ensure the number has at least 3 digits by padding from the left with zeros
+  const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+  // Extract the pound portion
+  const pounds = paddedPenceNumberString.substring(
+    0,
+    paddedPenceNumberString.length - 2
+  );
+
+  // Extract the pence portion and pad right if needed
+  const pence = paddedPenceNumberString
+    .substring(paddedPenceNumberString.length - 2)
+    .padEnd(2, "0");
+
+  // Return the formatted result
+  return `£${pounds}.${pence}`;
+}
+
+// Example usage:
+console.log(toPounds("399p"));
+console.log(toPounds("155p"));
+console.log(toPounds("75p"));

Sprint-2/4-mandatory-interpret/time-format.js

@@ -11,7 +11,7 @@ function formatTimeDisplay(seconds) {
   return `${pad(totalHours)}:${pad(remainingMinutes)}:${pad(remainingSeconds)}`;
 }
 
-// You will need to play computer with this example - use the Python Visualiser https://pythontutor.com/visualize.html#mode=edit
+// You will need to play computer with this example - use the Python Visualizer https://pythontutor.com/visualize.html#mode=edit
 // to help you answer these questions
 
 // Questions
@@ -20,15 +20,18 @@ function formatTimeDisplay(seconds) {
 // =============> write your answer here
 
 // Call formatTimeDisplay with an input of 61, now answer the following:
-
+// 3 times  which is once each for hours, minutes, and seconds.
 // b) What is the value assigned to num when pad is called for the first time?
 // =============> write your answer here
-
+// 0, because pad is first called with totalHours, which is 0.
 // c) What is the return value of pad is called for the first time?
 // =============> write your answer here
-
+// '00' pad(0) becomes "0" → padded to "00" using padStart(2, "0").
 // d) What is the value assigned to num when pad is called for the last time in this program?  Explain your answer
 // =============> write your answer here
-
+// 1, because the last call to pad is with remainingSeconds, which is 1.
 // e) What is the return value assigned to num when pad is called for the last time in this program?  Explain your answer
 // =============> write your answer here
+// "01",  pad(1) becomes "1" → padded to "01" using padStart(2, "0").
+
+// the final output of formatTimeDisplay(61) will be "00:01:01".