London | 25-ITP-September | Carlos Abreu | Sprint 2 | Coursework

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

@@ -1,13 +1,34 @@
 // Predict and explain first...
 //  =============> write your prediction here
 
+// Predict and explain first...
+//  =============> write your prediction here
+// This code will throw an error: "SyntaxError: Identifier 'str' has already been declared".
+// The reason is that the variable 'str' is declared twice — once as a function parameter
+// and again with `let str` inside the function. You cannot redeclare a parameter variable
+// using `let` or `const` in the same scope.
+
 // 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;
+// }
+
+// =============> write your explanation here
+
+// The error occurs because 'str' is already defined as a parameter to the function.
+// Using 'let str' again inside the function tries to redeclare it, which is not allowed.
+// We can fix this by either using a different variable name or by reassigning 'str'
+// directly without redeclaring it.
+
+// =============> write your new code here
 function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+// Example:
+console.log(capitalise("hello")); // Output: "Hello"
+

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

@@ -3,8 +3,15 @@
 // Why will an error occur when this program runs?
 // =============> write your prediction here
 
+// The code will throw a "SyntaxError: Identifier 'decimalNumber' has already been declared"
+// because the variable 'decimalNumber' is declared twice — once as a function parameter
+// and again with `const decimalNumber` inside the function.
+// Additionally, there will be a "ReferenceError: decimalNumber is not defined"
+// when trying to log it outside the function, since 'decimalNumber' only exists inside the function scope.
+
 // Try playing computer with the example to work out what is going on
 
+/**
 function convertToPercentage(decimalNumber) {
   const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
@@ -13,8 +20,55 @@ function convertToPercentage(decimalNumber) {
 }
 
 console.log(decimalNumber);
+*/
+
+
+
+// Predict and explain first...
+
+// Why will an error occur when this program runs?
+// =============> write your prediction here
+// The code will throw a "SyntaxError: Identifier 'decimalNumber' has already been declared"
+// because the variable 'decimalNumber' is declared twice — once as a function parameter
+// and again with `const decimalNumber` inside the function.
+// Additionally, there will be a "ReferenceError: decimalNumber is not defined"
+// when trying to log it outside the function, since 'decimalNumber' only exists inside the function scope.
+
+// 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;
+    }
+
+    console.log(decimalNumber);
+*/
 
 // =============> write your explanation here
 
+// The first error happens because 'decimalNumber' is redeclared inside the function
+// even though it’s already defined as a parameter. JavaScript does not allow
+// redeclaring parameters with `let` or `const`.
+// The second error happens because 'decimalNumber' is not defined in the global scope
+// — it only exists inside the function, so `console.log(decimalNumber)` cannot find it.
+
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+
+/**
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+console.log(convertToPercentage(0.5)); // Output: "50%"
+*/
+
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+console.log(convertToPercentage(0.5)); // Output: "50%"
+

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

@@ -4,17 +4,31 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+// This code will throw a SyntaxError because function parameters must be valid variable names,
+// not literal values like 3.
 
+/**
 function square(3) {
     return num * num;
 }
+*/
 
 // =============> write the error message here
+// SyntaxError: Unexpected number
+// (or "SyntaxError: Unexpected token '3'" depending on the environment)
 
 // =============> explain this error message here
-
+// The error occurs because JavaScript expects a variable name (like num or x) inside the parentheses 
+// of a function definition. You cannot use a number (3) as a parameter name — it’s not a valid identifier.
+// Function parameters act as variable placeholders for input values, so they must follow variable naming rules.
+//
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
 
+function square(num) {
+    return num * num;
+}
+
+console.log(square(3)); // Output: 9
 

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

@@ -1,14 +1,35 @@
 // Predict and explain first...
+// The console will print:
+// 320
+// The result of multiplying 10 and 32 is undefined
 
 // =============> write your prediction here
+// The first `console.log` inside the function prints the multiplication result (320).
+// However, since `multiply()` does not return anything, the outer `console.log` 
+// receives `undefined` as the value of the function call, leading to the message 
+// "The result of multiplying 10 and 32 is undefined".
 
+/**
 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 first `console.log` inside the function prints the multiplication result (320).
+// However, since `multiply()` does not return anything, the outer `console.log` 
+// receives `undefined` as the value of the function call, leading to the message 
+// "The result of multiplying 10 and 32 is undefined".
+//
+// To fix this, the function should `return` the result instead of just logging it.
 // 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)}`);
+// Output: "The result of multiplying 10 and 32 is 320"

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

@@ -1,13 +1,33 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// The console will print: "The sum of 10 and 32 is undefined"
+// This happens because the `return` statement ends the function immediately,
+// so the expression `a + b` after it is never executed. 
+// As a result, the function returns `undefined`.
 
+/**
 function sum(a, b) {
   return;
   a + b;
 }
 
+
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+*/
 
 // =============> write your explanation here
+// In JavaScript, when the interpreter encounters a `return` statement, 
+// it stops executing the rest of the function and immediately exits. 
+// Since there’s nothing after `return` on the same line, 
+// the function effectively returns `undefined`.
+// The expression `a + b` is never reached due to JavaScript’s automatic semicolon insertion.
+
 // 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)}`);
+// Output: "The sum of 10 and 32 is 42"
+

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

@@ -2,23 +2,42 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// The output will be:
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
+//
+// This happens because the function `getLastDigit` doesn’t use the argument passed to it. 
+// Instead, it always refers to the constant `num = 103`, 
+// so every time you call it, it converts 103 to a string and returns the last digit ("3").
 
-const num = 103;
+// Now run the code and compare the output to your prediction
+// =============> write the output here
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
+
+// Explain why the output is the way it is
+// =============> write your explanation here
+// The function `getLastDigit` ignores the argument being passed (like 42, 105, or 806) 
+// because it doesn’t have a parameter defined. 
+// Instead, it always uses the globally defined constant `num` (which is 103). 
+// Therefore, the function always returns the last digit of 103, which is "3".
 
-function getLastDigit() {
+// 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)}`);
 
-// Now run the code and compare the output to your prediction
-// =============> write the output here
-// Explain why the output is the way it is
-// =============> write your explanation here
-// Finally, correct the code to fix the problem
-// =============> write your new code here
-
 // This program should tell the user the last digit of each number.
 // Explain why getLastDigit is not working properly - correct the problem
+// The function was not working because it didn’t accept any parameters and 
+// was instead using the fixed global variable `num`. 
+// By adding a parameter to the function and using that instead, 
+// it now correctly calculates the last digit for any input number.
+

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

@@ -14,6 +14,34 @@
 // Then when we call this function with the weight and height
 // 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
-}
+}
+*/
+
+/**
+This function works by:
+
+Squaring the height.
+
+Dividing the weight by the squared height.
+
+Using toFixed(1) to round the BMI to 1 decimal place and converting it back to a number.
+*/
+
+// Function to calculate BMI
+function calculateBMI(weight, height) {
+    // Calculate BMI: weight divided by height squared
+    const bmi = weight / (height * height);
+
+    // Round the result to 1 decimal place and return
+    return Number(bmi.toFixed(1));
+}
+
+// Example usage:
+console.log(calculateBMI(70, 1.73)); // Output: 23.4
+console.log(calculateBMI(60, 1.6));  // Output: 23.4
+console.log(calculateBMI(90, 1.8));  // Output: 27.8
+
+

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

@@ -14,3 +14,25 @@
 // 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 to convert a string to UPPER_SNAKE_CASE
+function toUpperSnakeCase(str) {
+    // Replace spaces with underscores and convert to uppercase
+    return str.replace(/\s+/g, "_").toUpperCase();
+}
+
+// Example usage:
+console.log(toUpperSnakeCase("hello there"));         // Output: "HELLO_THERE"
+console.log(toUpperSnakeCase("lord of the rings"));   // Output: "LORD_OF_THE_RINGS"
+console.log(toUpperSnakeCase("javascript is fun"));   // Output: "JAVASCRIPT_IS_FUN"
+
+/**
+Explanation:
+
+str.replace(/\s+/g, "_") replaces all whitespace (spaces, tabs, etc.) with underscores.
+
+.toUpperCase() converts the resulting string to uppercase letters.
+
+The function returns the final string in UPPER_SNAKE_CASE
+*/
+

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

@@ -4,3 +4,56 @@
 // 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
+
+/**
+let penceString = "399p";
+
+let penceStringWithoutTrailingP = penceString.substring(
+  0,
+  penceString.length - 1
+);
+
+let paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+let pounds = paddedPenceNumberString.substring(
+  0,
+  paddedPenceNumberString.length - 2
+);
+
+let pence = paddedPenceNumberString
+  .substring(paddedPenceNumberString.length - 2)
+  .padEnd(2, "0");
+
+console.log(`£${pounds}.${pence}`);
+*/
+
+// Function to convert a pence string (like "399p") to pounds
+function toPounds(penceString) {
+    // Remove the trailing 'p'
+    let penceStringWithoutTrailingP = penceString.substring(
+        0,
+        penceString.length - 1
+    );
+
+    // Pad the string to ensure at least 3 digits
+    let paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+    // Extract pounds
+    let pounds = paddedPenceNumberString.substring(
+        0,
+        paddedPenceNumberString.length - 2
+    );
+
+    // Extract pence
+    let pence = paddedPenceNumberString
+        .substring(paddedPenceNumberString.length - 2)
+        .padEnd(2, "0");
+
+    return `£${pounds}.${pence}`;
+}
+
+// Example usage:
+console.log(toPounds("399p")); // Output: £3.99
+console.log(toPounds("5p"));   // Output: £0.05
+console.log(toPounds("1234p")); // Output: £12.34
+console.log(toPounds("50p"));   // Output: £0.50
+