Sheffield | 26-ITP-jan | Richard Frimpong | Sprint 2 | Structuring and Testing Data

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

@@ -4,10 +4,15 @@
 // 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
 // =============> 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

@@ -5,16 +5,22 @@
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
-  const percentage = `${decimalNumber * 100}%`;
+// function convertToPercentage(decimalNumber) {
+//   const decimalNumber = 0.5;
+//   const percentage = `${decimalNumber * 100}%`;
 
-  return percentage;
-}
+//   return percentage;
+// }
 
-console.log(decimalNumber);
+// console.log(decimalNumber);
 
 // =============> write your explanation here
 
 // 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

@@ -1,20 +1,29 @@
-
 // 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: Unexpected number
 
-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
+// The function parameter is written as 3, which is a number literal.
+// Function parameters must be variable names (identifiers).
+// JavaScript does not allow numbers as parameter names,
+// so it throws a SyntaxError before running the program.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
+function square(num) {
+    return num * num;
+}
 
+console.log(square(3));
 

Sprint-2/1-key-errors/answers.md

@@ -0,0 +1,101 @@
+# Sprint 2 - 1 Key Errors (Answers)
+
+## 0.js
+- Predicted error:
+- Actual error:
+- Why it happens:
+- Minimal fix:
+- Docs:
+
+## 1.js
+- Predicted error:
+- Actual error:
+- Why it happens:
+- Minimal fix:
+- Docs:
+
+## 2.js
+- Predicted error:
+- Actual error:
+- Why it happens:
+- Minimal fix:
+
+
+
+## 0.js
+
+- Predicted error: SyntaxError (variable redeclaration)
+
+- Actual error: SyntaxError: Identifier 'str' has already been declared
+
+- Why it happens:  
+  The function parameter `str` is already declared. Inside the function, `let str = ...` attempts to redeclare the same variable in the same scope. JavaScript does not allow redeclaration of variables using `let`.
+
+- Minimal fix:  
+  Remove the `let` and return the new string directly:
+
+  ```js
+  function capitalise(str) {
+    return `${str[0].toUpperCase()}${str.slice(1)}`;
+  }
+
+  - Docs:  
+  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let
+
+
+
+  ## 1.js
+- Predicted error: SyntaxError (variable redeclaration)
+
+- Actual error: SyntaxError: Identifier 'decimalNumber' has already been declared
+
+- Why it happens:  
+  The function parameter `decimalNumber` is already declared. Inside the function, `const decimalNumber = 0.5;` attempts to redeclare the same variable in the same scope. JavaScript does not allow redeclaration using `const`.
+
+  There is also a second issue:  
+  `console.log(decimalNumber);` is outside the function, and `decimalNumber` is not defined in the global scope. This would cause a ReferenceError.
+
+- Concepts tested:  
+  Variable scope, function parameters, redeclaration rules, global vs local variables.
+
+  function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+console.log(convertToPercentage(0.5));
+
+
+
+
+## 2.js
+
+- Predicted error: SyntaxError (invalid function parameter)
+
+- Actual error: SyntaxError: Unexpected number
+
+- Why it happens:  
+  The function is declared as `function square(3)`.  
+  Function parameters must be variable names (identifiers), not literal values.  
+  The number `3` is not a valid parameter name, so JavaScript throws a syntax error.
+
+- Concept tested:  
+  Function declaration syntax and valid parameter identifiers.
+
+- Minimal fix:
+
+```js
+function square(number) {
+  return number * number;
+}
+
+console.log(square(3));
+
+
+
+
+
+
+
+
+

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

@@ -1,14 +1,29 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// The function will print 320 from inside multiply,
+// but the final console.log will show "undefined"
+// because multiply does not return a value.
 
-function multiply(a, b) {
-  console.log(a * b);
-}
+// function multiply(a, b) {
+//   console.log(a * b);
+// }
 
-console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
+// console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
 // =============> write your explanation here
+// The function multiply only logs the result using console.log,
+// but it does not return the value.
+// Since it does not return anything, JavaScript returns undefined by default.
+// Therefore, the template string inserts undefined.
 
 // 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 +1,27 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// The function will return undefined because the return statement
+// is followed by a line break. JavaScript inserts a semicolon automatically,
+// so the function exits before a + b is executed.
 
-function sum(a, b) {
-  return;
-  a + b;
-}
+// function sum(a, b) {
+//   return;
+//   a + b;
+// }
 
-console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+// console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// The return statement is on its own line.
+// JavaScript automatically inserts a semicolon after return.
+// This means the function returns undefined immediately,
+// and the expression a + b is never 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

@@ -2,23 +2,38 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// The function will always return 3 because it uses the global variable num (103).
+// So all outputs will show 3 regardless of the input.
 
-const num = 103;
+// const num = 103;
 
-function getLastDigit() {
-  return num.toString().slice(-1);
-}
+// function getLastDigit() {
+//   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)}`);
+// 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 does not take a parameter, so it ignores the values passed in.
+// It always uses the global variable num (which is 103).
+// Therefore, it always returns the last digit of 103, which is 3.
+
 // 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
+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)}`);

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

@@ -15,5 +15,6 @@
 // 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
-}
+  const bmi = weight / (height * height);
+  return Number(bmi.toFixed(1));
+}

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

@@ -14,3 +14,13 @@
 // 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();
+}
+
+// Test cases
+console.log(toUpperSnakeCase("hello there")); // HELLO_THERE
+console.log(toUpperSnakeCase("lord of the rings")); // LORD_OF_THE_RINGS
+

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

@@ -4,3 +4,31 @@
 // 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}`;
+}
+
+// Test cases
+console.log(toPounds("399p"));   // £3.99
+console.log(toPounds("5p"));     // £0.05
+console.log(toPounds("1200p"));  // £12.00
+

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

@@ -11,24 +11,21 @@ function formatTimeDisplay(seconds) {
   return `${pad(totalHours)}:${pad(remainingMinutes)}:${pad(remainingSeconds)}`;
 }
 
-// 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
+// =============> 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
+// =============> 0 (the first call is pad(totalHours), and totalHours is 0 when seconds = 61)
 
-// 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?
+// =============> "00" (0 becomes "0" then padStart(2,"0") makes it "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
+// =============> 1 (the last call is pad(remainingSeconds), and 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
+// e) What is the return value assigned to num when pad is called for the last time in this program? Explain your answer
+// =============> "01" ("1" is padded to two digits using padStart)