London | 26-ITP-Jan | Xuanming Hu | Sprint 2 | Coursework

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

@@ -1,13 +1,18 @@
 // Predict and explain first...
 //  =============> write your prediction here
-
+// It will crash with a SyntaxError. We can't use 'let' to declare 'str' because 'str' is already taken by the function parameter.
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
-
+/* I commented this out so it doesn't crash:
 function capitalise(str) {
   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
-
+*/
 // =============> write your explanation here
+//The error confirms "str has already been declared". Function parameters act as local variables, creating a naming conflict with `let str`.
 // =============> write your new code here
+function capitalise(str) {
+  return `${str[0].toUpperCase()}${str.slice(1)}`;
+}
+console.log(capitalise("hello"));

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

@@ -2,9 +2,9 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
-
+// It will crash for two reasons. 1. Trying to log a local variable 'decimalNumber' outside its function. 2. Trying to re-declare the parameter 'decimalNumber' using 'const' inside the function.
 // Try playing computer with the example to work out what is going on
-
+/* Commented out broken code:
 function convertToPercentage(decimalNumber) {
   const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
@@ -13,8 +13,12 @@ function convertToPercentage(decimalNumber) {
 }
 
 console.log(decimalNumber);
-
+*/
 // =============> write your explanation here
-
+// 'decimalNumber' is scoped to the function, so console.log outside can't see it (ReferenceError). Inside, re-declaring the parameter with 'const' causes a SyntaxError. Also, the function was never actually called.
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  return `${decimalNumber * 100}%`;
+}
+console.log(convertToPercentage(0.5));

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

@@ -4,17 +4,22 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
-
+// Syntax error. We put a hardcoded number '3' where a parameter name (like 'num') should be.
+/* Commented out the broken code so it doesn't crash:
 function square(3) {
     return num * num;
 }
-
+*/
 // =============> write the error message here
-
+// SyntaxError: Unexpected number
 // =============> explain this error message here
-
+// Function definitions require variable names as parameters to act as placeholders, not literal values.
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
-
+function square(num) {
+  return num * num;
+}
+console.log(square(3)); 
+console.log(square(4));
 

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

@@ -1,14 +1,19 @@
 // Predict and explain first...
 
 // =============> write your prediction here
-
+//It will print "320", followed by "The result... is undefined". The function lacks a return value.
+/* Commented out the broken code:
 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
-
+// `console.log` just prints to the screen. Without a `return` statement, the function evaluates to `undefined`, which gets injected into the template literal.
 // 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

@@ -1,13 +1,19 @@
 // Predict and explain first...
 //  =============> write your prediction here
-
+// It will print "undefined". The 'return;' statement stops the function immediately before it even looks at 'a + b'.
+/* Commented out the broken code:
 function sum(a, b) {
   return;
   a + b;
 }
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
-
+*/
 // =============> write your explanation here
+// The 'return' keyword instantly exits the function. Since nothing is attached to it, it returns 'undefined'. The 'a + b;' line is dead code that never gets executed.
 // Finally, correct the code to fix the problem
 //  =============> 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

@@ -2,7 +2,8 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
-
+// It will always print "3" for every log. The function ignores the numbers we pass in and blindly uses the global 'num' (103).
+/* Commented out the broken code:
 const num = 103;
 
 function getLastDigit() {
@@ -12,13 +13,22 @@ function getLastDigit() {
 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
+// The function lacks a parameter in its definition. Therefore, it ignores the arguments (42, 105, 806) and always falls back to the globally defined 'num' which is 103.
 // Finally, correct the code to fix the problem
 // =============> write your new code here
-
+function getLastDigit(number) {
+  return number.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

@@ -13,7 +13,14 @@
 // Given someone's weight in kg and height in metres
 // Then when we call this function with the weight and height
 // It should return their Body Mass Index to 1 decimal place
-
+/**
+ * Calculates the Body Mass Index (BMI).
+ * @param {number} weight - The weight in kilograms (kg).
+ * @param {number} height - The height in meters (m).
+ */
 function calculateBMI(weight, height) {
     // return the BMI of someone based off their weight and height
-}
+    let bmi = weight / (height * height);
+    return parseFloat(bmi.toFixed(1));
+}
+console.log(`The BMI is: ${calculateBMI(70, 1.73)}`);

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

@@ -14,3 +14,8 @@
 // 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(" ", "_");
+}
+console.log(toUpperSnakeCase("hello there"));
+console.log(toUpperSnakeCase("lord of the rings"));

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

@@ -4,3 +4,16 @@
 // 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("50p"));
+console.log(toPounds("399p"));
+console.log(toPounds("5p"));
+console.log(toPounds("12345p"));

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

@@ -10,25 +10,25 @@ function formatTimeDisplay(seconds) {
 
   return `${pad(totalHours)}:${pad(remainingMinutes)}:${pad(remainingSeconds)}`;
 }
-
+console.log(formatTimeDisplay(61));
 // You will need to play computer with this example - use the Python Visualiser https://pythontutor.com/visualize.html#mode=edit
 // to help you answer these questions
 
 // 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
+// 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
+// Answer: 1. The last call evaluates `pad(remainingSeconds)`. Since 61 % 60 equals 1, the value of remainingSeconds passed to `num` is 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
+// Answer: "01". The function takes the number 1, converts it to a string, and pads it with a leading "0" to make it 2 characters long.

Sprint-2/5-stretch-extend/format-time.js

@@ -3,23 +3,28 @@
 // Your task is to write tests for as many different groups of input data or edge cases as you can, and fix any bugs you find.
 
 function formatAs12HourClock(time) {
-  const hours = Number(time.slice(0, 2));
-  if (hours > 12) {
-    return `${hours - 12}:00 pm`;
+  let hours = Number(time.slice(0, 2));
+  const minutes = time.slice(3, 5);
+
+  const period = hours >= 12 ? "pm" : "am";
+
+  hours = hours % 12;
+  if (hours === 0) {
+    hours = 12;
   }
-  return `${time} am`;
+
+  const paddedHours = hours.toString().padStart(2, "0");
+
+  return `${paddedHours}:${minutes} ${period}`;
 }
 
-const currentOutput = formatAs12HourClock("08:00");
-const targetOutput = "08:00 am";
-console.assert(
-  currentOutput === targetOutput,
-  `current output: ${currentOutput}, target output: ${targetOutput}`
-);
+console.assert(formatAs12HourClock("08:00") === "08:00 am", "Morning time failed");
+console.assert(formatAs12HourClock("23:00") === "11:00 pm", "Night time failed");
 
-const currentOutput2 = formatAs12HourClock("23:00");
-const targetOutput2 = "11:00 pm";
-console.assert(
-  currentOutput2 === targetOutput2,
-  `current output: ${currentOutput2}, target output: ${targetOutput2}`
-);
+console.assert(formatAs12HourClock("00:00") === "12:00 am", "Midnight edge case failed");
+console.assert(formatAs12HourClock("00:15") === "12:15 am", "Past midnight failed");
+
+console.assert(formatAs12HourClock("12:00") === "12:00 pm", "Noon edge case failed");
+console.assert(formatAs12HourClock("12:30") === "12:30 pm", "Past noon failed");
+
+console.assert(formatAs12HourClock("13:45") === "01:45 pm", "Padding hour formatting failed");