Complete Sprint 2 mandatory exercises

Author: codebyra

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

@@ -1,13 +1,17 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// Prediction: The program will throw a SyntaxError because 'str' is declared twice in the same function.
 
 // 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)}`;
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
 
-// =============> write your explanation here
+console.log(capitalise("hello"));
+
+// Explanation: The function parameter is already called 'str'. Declaring another variable with 'let str' inside the same function is not allowed, so JavaScript throws a SyntaxError.
+
+// Finally, correct the code to fix the problem
 // =============> write your new code here

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

@@ -1,20 +1,19 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// Prediction: The program will throw a SyntaxError because 'decimalNumber' is declared twice. If that is fixed, it will then throw a ReferenceError because 'decimalNumber' is used outside the function where it is defined.
 
 // 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);
+console.log(convertToPercentage(0.5));
 
-// =============> write your explanation here
+// Explanation: The function parameter is already called 'decimalNumber', so declaring 'const decimalNumber' again is not allowed. Also, 'decimalNumber' only exists inside the function, so trying to use it outside the function causes a ReferenceError.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here

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

@@ -1,20 +1,20 @@
-
 // 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
+// Prediction: The program will throw a SyntaxError because function parameters cannot be numbers. They must be valid variable names.
 
-function square(3) {
-    return num * num;
+function square(num) {
+  return num * num;
 }
 
-// =============> write the error message here
+console.log(square(3));
+
+// Error message:
+// SyntaxError: Unexpected number
 
-// =============> explain this error message here
+// Explanation: The parameter '3' is not a valid parameter name. Function parameters must be variable names so that values can be passed into the function.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
-
-

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

@@ -1,14 +1,14 @@
 // Predict and explain first...
 
-// =============> write your prediction here
+// Prediction: The function will print 320, but the final message will show "undefined".
 
 function multiply(a, b) {
-  console.log(a * b);
+  return a * b;
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
-// =============> write your explanation here
+// Explanation: The original function used console.log() instead of return. console.log() displays the result on the screen but does not return a value, so the function returned undefined. Changing console.log() to return fixes the problem.
 
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+// =============> write your new code here

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

@@ -1,13 +1,14 @@
 // Predict and explain first...
-//  =============> write your prediction here
+
+// Prediction: The function will return undefined because the return statement ends before a + b is executed.
 
 function sum(a, b) {
-  return;
-  a + b;
+  return a + b;
 }
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
-// =============> write your explanation here
+// Explanation: In the original code, JavaScript automatically inserts a semicolon after `return` because it is on its own line. This means the function returns undefined immediately, and `a + b` is never executed.
+
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+// =============> write your new code here

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

@@ -1,11 +1,10 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// Prediction:
+// The program will print 3 for all three lines because the function always uses the constant 'num', which is 103.
 
-const num = 103;
-
-function getLastDigit() {
+function getLastDigit(num) {
   return num.toString().slice(-1);
 }
 
@@ -14,11 +13,17 @@ 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
+// Output:
+// The last digit of 42 is 2
+// The last digit of 105 is 5
+// The last digit of 806 is 6
+
 // Explain why the output is the way it is
-// =============> write your explanation here
+// Explanation:
+// The original function always used the constant 'num' (103), so it always returned 3. By giving the function a parameter called 'num', it now uses the value passed into the function each time it is called.
+
 // 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
+// Explain why getLastDigit is not working properly - correct the problem.

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

@@ -15,5 +15,5 @@
 // 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 (weight / (height * height)).toFixed(1);
+}

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

@@ -14,3 +14,7 @@
 // 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(text) {
+  return text.toUpperCase().replaceAll(" ", "_");
+}

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

@@ -4,3 +4,23 @@
 // 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) {
+  const penceStringWithoutTrailingP = penceString.substring(
+    0,
+    penceString.length - 1
+  );
+
+  const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+  const pounds = paddedPenceNumberString.substring(
+    0,
+    paddedPenceNumberString.length - 2
+  );
+
+  const pence = paddedPenceNumberString
+    .substring(paddedPenceNumberString.length - 2)
+    .padEnd(2, "0");
+
+  return `£${pounds}.${pence}`;
+}

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

@@ -21,18 +21,20 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
+// Answer: 3 times
 
 // Call formatTimeDisplay with an input of 61, now answer the following:
 
 // b) What is the value assigned to num when pad is called for the first time?
-// =============> write your answer here
+// Answer: 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?
+// Answer: "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
+// Answer: 1
+// Explanation: The last call to pad is pad(remainingSeconds). When the input is 61 seconds, the remaining seconds are 1.
 
-// 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
+// Answer: "01"
+// Explanation: The pad function adds a leading zero to numbers with only one digit, so 1 becomes "01".