Complete JavaScript practice exercises

Author: fromonda

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

@@ -1,5 +1,6 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// The issue is that return is on one line and a + b is on the next.
+// Therefore, a + b is never returned.
 
 function sum(a, b) {
   return;
@@ -8,6 +9,11 @@ function sum(a, b) {
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
-// =============> write your explanation here
+// After running the code, the sum of 10 and 32 is undefined.
+// JavaScript inserts a semicolon after return when a + b is placed on the next line.
+// This causes the function to return before calculating the sum.
+
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+//  function sum(a, b) {
+//    return a + b;
+//  }

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

@@ -1,7 +1,7 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// I believe that in each case, the output will be the last digit of 103, which is 3.
 
 const num = 103;
 
@@ -14,11 +14,24 @@ 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
+// The function getLastDigit() does not accept a parameter.
+// Consequently, it always uses the global variable num, whose value is 103.
+
 // Finally, correct the code to fix the problem
-// =============> write your new code here
+// const num = 103;
+// 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
+// getLastDigit() is not working properly because it always uses the global num variable (103).
+// I added num as a parameter so that the function can accept the value passed as an argument.

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

@@ -15,5 +15,8 @@
 // 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
-}
+    let bmi = weight / (height * height);
+    return bmi.toFixed(1);
+}
+
+console.log(calculateBMI(70, 1.73));

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

@@ -14,3 +14,10 @@
 // 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(input) {
+    return input.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 +4,27 @@
 // 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}`;
+}
+
+console.log(toPounds("399p"));
+console.log(toPounds("5p"));
+console.log(toPounds("1200p"));

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

@@ -21,18 +21,19 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
+// pad() is called 3 times because it is used once for hours, once for minutes, and once for seconds.
 
 // 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
+// Because the first call to pad() is pad(totalHours), and formatTimeDisplay(61) calculates totalHours as 0, the value passed to pad() as num is 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 called for the first time?
+// When pad() is called for the first time, num is 0 because totalHours is 0.
+// The function converts it to a string and adds a leading zero, so the return value is "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
+// Because the last call to pad() is pad(remainingSeconds) and formatTimeDisplay(61) calculates remainingSeconds as 1 (61 % 60 = 1), the value passed into pad() as num is 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
+// The return value of pad() when it is called for the last time is "01" because num is 1, and the function pads numbers by adding a leading zero.