London | 25_ITP-Sept | Samuel Tarawally | Sprint 2 | Coursework

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

@@ -1,13 +1,20 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// SyntaxError: Cannot redeclare parameter 'str' inside function body
 
 // 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;
-}
+// function capitalise(str) {
+//   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+//   return str;
+// }
 
 // =============> write your explanation here
+// SyntaxError: Identifier 'str' has already been declared - parameter cannot be redeclared with let/const/var
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Redeclared_parameter
+
 // =============> write your new code here
+function capitalise(str) {
+  return `${str[0].toUpperCase()}${str.slice(1)}`;
+}

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

@@ -2,19 +2,24 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// SyntaxError: Cannot redeclare parameter 'decimalNumber' inside function body
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
-  const percentage = `${decimalNumber * 100}%`;
-
-  return percentage;
-}
-
-console.log(decimalNumber);
+// function convertToPercentage(decimalNumber) {
+//   const decimalNumber = 0.5;
+//   const percentage = `${decimalNumber * 100}%`;
+//   return percentage;
+// }
+// console.log(decimalNumber);
 
 // =============> write your explanation here
+// SyntaxError: Identifier 'decimalNumber' has already been declared - parameter cannot be redeclared
+// Also, console.log(decimalNumber) would cause ReferenceError - variable only exists inside function scope
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Redeclared_parameter
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  return `${decimalNumber * 100}%`;
+}

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

@@ -1,20 +1,23 @@
-
 // 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
+// SyntaxError: Function parameters must be valid identifiers, not number literals
 
-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
+// Parameters must be valid identifiers (start with letter/underscore/$), not numbers
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Unexpected_token
 
 // 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

@@ -1,6 +1,8 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// Output: "320" then "The result of multiplying 10 and 32 is undefined"
+// Function logs but doesn't return, so template literal receives undefined
 
 function multiply(a, b) {
   console.log(a * b);
@@ -9,6 +11,11 @@ function multiply(a, b) {
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
 // =============> write your explanation here
+// Bug: console.log() prints but doesn't return a value - functions without return give undefined
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/return
 
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+function multiply(a, b) {
+  return a * b;
+}

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

@@ -1,5 +1,7 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// Output: "The sum of 10 and 32 is undefined"
+// Return statement has no value, so returns undefined. Expression "a + b" is unreachable code
 
 function sum(a, b) {
   return;
@@ -9,5 +11,11 @@ function sum(a, b) {
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// Bug: return; exits immediately without a value (returns undefined). Code after return never executes
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/return
+
 // 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

@@ -2,6 +2,7 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// All outputs will be "3" because function has no parameter and always uses global num (103)
 
 const num = 103;
 
@@ -15,10 +16,20 @@ 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
+// Bug: Function has no parameter, so arguments (42, 105, 806) are ignored. Always uses global num (103)
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice
+
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function getLastDigit(number) {
+  return number.toString().slice(-1);
+}
 
 // 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 +15,5 @@
 // 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 Number((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(str) {
+  return str.replaceAll(" ", "_").toUpperCase();
+}

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

@@ -4,3 +4,19 @@
 // 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

@@ -18,17 +18,22 @@ function formatTimeDisplay(seconds) {
 
 // a) When formatTimeDisplay is called how many times will pad be called?
 // =============> write your answer here
+// 3 times: pad(totalHours), pad(remainingMinutes), pad(remainingSeconds)
 
 // 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
+// 0 (totalHours for 61 seconds = 0 hours)
 
 // c) What is the return value of pad is called for the first time?
 // =============> write your answer here
+// "00" (0.toString().padStart(2, "0"))
 
 // 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
+// 1 (remainingSeconds for 61 seconds: 61 % 60 = 1)
 
 // e) What is the return value assigned to num when pad is called for the last time in this program?  Explain your answer
 // =============> write your answer here
+// "01" (1.toString().padStart(2, "0"))