London | 26-ITP-May | Gideon Defar | Sprint 2 | Acoursework/sprint 2`

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

@@ -4,10 +4,17 @@
 // 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;
+// }
+
+// =============> SyntaxError: Identifier 'str' has already been declared, 
+// So In JavaScript, we cannot declare a let variable with the same name as an existing parameter within the same scope. This causes a SyntaxError
+
+// =============> 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
+console.log(capitalise("hello"));

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

@@ -5,16 +5,27 @@
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
-  const percentage = `${decimalNumber * 100}%`;
+// function convertToPercentage(decimalNumber) {
+//   const decimalNumber = 0.5;
+//   const percentage = `${decimalNumber * 100}%`;
 
-  return percentage;
-}
+//   return percentage;
+// }
+
+// console.log(decimalNumber);
 
-console.log(decimalNumber);
+// =============> JavaScript does not allow a parameter and a const variable inside the same scope to have the same name, so it gives an error.
+//console.log(decimalNumber);
 
-// =============> write your explanation here
+//decimalNumber only exists inside the function. It is a local variable, so it cannot be accessed outside the function. This causes a ReferenceError.
 
 // 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));

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

@@ -5,16 +5,22 @@
 
 // =============> 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
+//A SyntaxError will occur because `3` cannot be used as a function parameter name.
+//Function parameters must be valid variable names, 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(3));

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

@@ -1,14 +1,26 @@
-// Predict and explain first...
-
 // =============> write your prediction here
+/*
+The function should return the multiplication result so that
+the returned value can be used inside the template literal.
+*/
+// function multiply(a, b) {
+//   return a * b;
+// }
 
-function multiply(a, b) {
-  console.log(a * b);
-}
-
-console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
+// console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
 // =============> write your explanation here
-
+/*
+The original function used console.log() instead of return.
+console.log() displays 320 but does not give the value back to
+the calling code. Therefore multiply(10, 32) returned undefined.
+Using return allows the value 320 to be inserted into the string.
+*/
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+// =============> 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)}`);

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

@@ -1,13 +1,20 @@
-// Predict and explain first...
-//  =============> write your prediction here
+// =============> write your prediction here
 
-function sum(a, b) {
-  return;
-  a + b;
-}
-
-console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+/*The program will output:
+"The sum of 10 and 32 is undefined"
+because the function returns before performing the addition.*/
 
 // =============> write your explanation here
+
+/*The `return` statement immediately stops the function.
+Because it has no value after it, the function returns `undefined`.
+The `a + b` line is never executed.*/
+
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+// =============> write your new code here
+
+function sum(a, b) {
+  return a + b;
+}
+
+console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);

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

@@ -1,24 +1,38 @@
 // Predict and explain first...
 
-// Predict the output of the following code:
+// Predict the output of the following code: The function will return "3" every time.
 // =============> Write your prediction here
 
-const num = 103;
+/*Even though 42, 105, and 806 are passed to getLastDigit(),
+the function does not have a parameter to receive those values.
+Instead, it always uses the global variable num, whose value is 103.
+Therefore, all three lines will output 3.*/
 
-function getLastDigit() {
-  return num.toString().slice(-1);
-}
+// const num = 103;
 
-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)}`);
+// 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)}`);
 
 // 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
 // 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 +15,7 @@
 // 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
-}
+    const bmi = weight / (height * height);
+    return Math.round(bmi * 10) / 10;
+}
+console.log(calculateBMI(70, 1.73));

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

@@ -14,3 +14,9 @@
 // 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(str) {
+  return str.toUpperCase().replaceAll(" ", "_");
+}
+
+console.log(toUpperSnakeCase("hello there"));
+console.log(toUpperSnakeCase("lord of the rings"));

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

@@ -4,3 +4,31 @@
 // 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
+// This program takes a string representing a price in pence.
+// The program then builds up a string representing the price in pounds.
+
+// 1. Initialise a string variable with the value "399p"
+const penceString = "399p";
+
+// 2. Remove the trailing "p" from the string
+const penceStringWithoutTrailingP = penceString.substring(
+  0,
+  penceString.length - 1
+);
+
+// 3. Make sure the pence value has at least 3 digits
+const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+// 4. Get the pounds part by removing the last two digits
+const pounds = paddedPenceNumberString.substring(
+  0,
+  paddedPenceNumberString.length - 2
+);
+
+// 5. Get the pence part (the last two digits)
+const pence = paddedPenceNumberString
+  .substring(paddedPenceNumberString.length - 2)
+  .padEnd(2, "0");
+
+// 6. Display the final price
+console.log(`£${pounds}.${pence}`);

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

@@ -21,18 +21,18 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
-
-// Call formatTimeDisplay with an input of 61, now answer the following:
+// =============> 3 times
 
 // b) What is the value assigned to num when pad is called for the first time?
-// =============> write your answer here
+// =============> 0
 
-// c) What is the return value of pad is called for the first time?
-// =============> write your answer here
+// c) What is the return value of pad when it is called for the first time?
+// =============> "00"
 
-// 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
+// d) What is the value assigned to num when pad is called for the last time in this program? Explain your answer
+// =============> 1, because formatTimeDisplay(61) has 1 remaining second,
+// and the last call to pad is pad(remainingSeconds).
 
-// e) What is the return value of pad when it is called for the last time in this program?  Explain your answer
-// =============> write your answer here
+// e) What is the return value of pad when it is called for the last time in this program? Explain your answer
+// =============> "01", because pad adds a zero to the beginning of "1"
+// to make it two characters long.