London | 26-ITP-May | Anita Amirhaeri | Sprint 2 | Structuring-and-Testing-Data

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

@@ -1,5 +1,10 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// The error in the code occurs because the variable 'str' is being declared twice within the same scope.
+// The first declaration is in the function parameter, and the second declaration is inside the function body.
+// This causes a syntax error because JavaScript does not allow redeclaration of variables in the same scope using 'Let'.
+// To fix this error, we can simply remove the 'Let' keyword from the second declaration of 'str' inside the function body.
+// The correction would be to assign the new variable without redeclaration, like this: 'str = `${str[0].toUpperCase()}${str.slice(1)}`;'.
+// This way, we are reassigning the value of 'str' without trying to declare it again.
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
@@ -9,5 +14,12 @@ function capitalise(str) {
   return str;
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+// The error in the code occurs because the variable 'str' is being declared twice within the same scope.
+// The first declaration is in the function parameter, and the second declaration is inside the function body.
+// This causes a syntax error because JavaScript does not allow redeclaration of variables in the same scope using 'Let'.
+// To fix this error, I can rename the variable inside the function body to something else, like 'caps', to avoid redeclaration.
+
+function capitalise(str) {
+  let caps = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return caps;
+}

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

@@ -1,7 +1,7 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// Declaring a variable with the same name as the function parameter in the function body causes a SyntaxError.
 
 // Try playing computer with the example to work out what is going on
 
@@ -14,7 +14,13 @@ function convertToPercentage(decimalNumber) {
 
 console.log(decimalNumber);
 
-// =============> write your explanation here
+// After running the code, the following error message was displayed:
+// Uncaught SyntaxError: Identifier 'decimalNumber' has already been declared
 
 // 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

@@ -3,18 +3,19 @@
 
 // this function should square any number but instead we're going to get an error
 
-// =============> write your prediction of the error here
+// The error occurs because 3 is used as a function parameter.
+// Parameters must be variable names, whereas values are passed as arguments when the function is called.
 
 function square(3) {
     return num * num;
 }
 
-// =============> write the error message here
+// Uncaught SyntaxError: Unexpected number
 
-// =============> explain this error message here
+// The parser evaluates the code as a SyntaxError before execution because a value cannot be used as a parameter name in JavaScript.
 
 // Finally, correct the code to fix the problem
 
-// =============> write your new code here
-
-
+// function square(num) {
+//    return num * num;
+// }

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

@@ -1,14 +1,20 @@
 // Predict and explain first...
 
-// =============> write your prediction here
+// The result of multiplying 10 and 32 is expected to be undefined because the multiply() function does not return the result.
+// It only prints it using console.log().
 
 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
+// After running the code, the result of multiplying 10 and 32 is undefined indeed.
+// The problem occurs because the function has no return statement to send a value back to where the function was called.
 
 // 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)}`);

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 +14,9 @@
 // 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(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 +4,26 @@
 // 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.