London | 26-ITP-JAN | Shuheda Begum | Sprint 2 | Structuring and Testing Data

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

@@ -1,13 +1,41 @@
 // Predict and explain first...
-//  =============> write your prediction here
+// I predict when this code runs, there will be a SyntaxError before the function executes. 
+// This is because the identifier 'str' has already been declared.
 
 // call the function capitalise with a string input
+// capitalise("hello");
+
+
 // interpret the error message and figure out why an error is occurring
+// Uncaught SyntaxError: Unexpected identifier 'string' - this is the error message. 
+// This error is occuring because the variable 'str' is being redeclared within the function, which is not allowed in JavaScript.
+// The duplicate use if 'str' is causing the syntax error.
+
+
+//function capitalise(str) {
+  //let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  //return str;
+//}
+
+// The issue is variable redeclaration.
+// str is the function parameter.
+// let str tries to create a new variable with the same name.
+// JavaScript does not allow redeclaring a variable in the same scope.
+// As a result, the code throws a SyntaxError when it encounters the second 'str' declaration.
 
+// New code without the error:
+
+// 0.js — fully fixed version
 function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
+  if (!str) return str; // handles empty string
+  return str[0].toUpperCase() + str.slice(1);
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+// Test it
+console.log(capitalise("hello")); // should print "Hello"
+console.log(capitalise("world")); // should print "World"
+console.log(capitalise(""));      // should print ""
+
+
+
+

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

@@ -1,20 +1,29 @@
 // Predict and explain first...
-
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// I predict an error will occur when this program runs because the variable 'decimalNumber' is already declared inside the function 'convertToPercentage' and cannot be redeclared.
 
 // Try playing computer with the example to work out what is going on
+// When the 'function convertToPercentage(decimalNumber)' is created, Javascript already creates a variable called decimalNumber. then, inside the function, 'const decimalNumber = 0.5' tries to create another variable with the same name. This casues a syntax error because you cannot declare two variables with the same name in the same scope. 
 
-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
+// Write your explanation here
+// I redelcared the parameter decimalNumber using const. 
+// I tried to log decimalNumber outside its scope.
+// The variables declared inside the function are not available outside unless they are returned.
 
 // 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)); // "50%"

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

@@ -1,20 +1,32 @@
 
 // Predict and explain first BEFORE you run any code...
+// This function should square any number but instead we're going to get an error
 
-// this function should square any number but instead we're going to get an error
+// Write your prediction of the error here:
+// I predict that the error will be a syntax error because the parameter '3' is not a valid variable name.
+// When you define a function,, the thing inside the parentahese must be a parameter name, NOT a number.
 
-// =============> write your prediction of the error here
+// function square(3) {
+   // return num * num;
+// }
 
-function square(3) {
-    return num * num;
-}
+// Write the error message here
+// SyntaxError: Unexpected number
 
-// =============> write the error message here
-
-// =============> explain this error message here
+// Explain the error messge here:
+// When defining a function, inside the parentheses, you need to put a parameter name, which is a variable.
+// In this case, '3' is not a valid parameter name because it is a number, not a variable. 
+// This causes a syntax error because Javascript expects a name, not a number.
 
 // Finally, correct the code to fix the problem
+// Write your new code here
+
+function square(num) {
+    return num * num;
+}
+
+console.log(square(3));  // 9
+console.log(square(5));  // 25
 
-// =============> write your new code here
 
 

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

@@ -1,14 +1,24 @@
-// Predict and explain first...
+// Predict and explain first...write your prediction here
+// I predict, when the code runs, it will print 320, but it will also print "The result of multiplying 10 and 32 is undefined".
 
-// =============> write your prediction here
+//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
+// The function multiply(a, b) logs the result of a * b to the console but does not return a value.
+// When multiply(10, 32) is called within the template literal, it logs 320 to the console but returns undefined.
+// Therefore, inside the template literal, the value is undefined, which is why the final output becomes "The result of multiplying 10 and 32 is undefined".
+
+// Finally, correct the code to fix the problem
+// Write your new code here
+// To fix the problem, the function should return the result instead of logging it.
 
 function multiply(a, b) {
-  console.log(a * b);
+  return a * b;
 }
 
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
-// =============> write your explanation here
-
-// Finally, correct the code to fix the problem
-//  =============> write your new code here

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

@@ -1,13 +1,23 @@
-// Predict and explain first...
-//  =============> write your prediction here
+// Predict and explain first...write your prediction here
+// I think the code will return undefined.
 
-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
+// When JavaScript sees the 'return' statement, it immediately stopd the function. It does NOT continue to the next line.
+// So this part, 'a+b;' never runs. To return the sum of a and b, we need to put it on the same line as the return.
+// Like the: 'return a + b;'
 
-// =============> write your explanation here
 // 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

@@ -1,24 +1,43 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// Write your prediction here
+// I think the output will be 'The last digit of 42 is 2', 'The last digit of 105 is 5', and 'The last digit of 806 is 6'.
+// I think this will happen because the getLastDigit function is supposed to take a number, convert it to a string, and then return the last charecter of that string, which should be the last digit. 
 
-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)}`);
+
+// Now run the code and compare the output to your prediction
+// Write the output here
+// The output is:
+// 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 output is 3 for all numbers because the function getLastDigit is not taking any parameters. It always uses the global variable `num` which is set to 103. So it always returns the last digit of 103, which is 3.
+
+// 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)}`);
 
-// Now run the code and compare the output to your prediction
-// =============> write the output here
-// Explain why the output is the way it is
-// =============> write your explanation here
-// 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
+// The function did not accept a parameter. It was a fixed variable (num = 103), so it always returned the last digit of 103.

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

@@ -14,6 +14,30 @@
 // Then when we call this function with the weight and height
 // It should return their Body Mass Index to 1 decimal place
 
-function calculateBMI(weight, height) {
+//function calculateBMI(weight, height) {
     // return the BMI of someone based off their weight and height
-}
+// }
+
+// Notes:
+// BMI =  weight ÷ (height x height)                                        
+// eg. BMI = 70kg ÷ (1.73m x 1.73)
+// BMI = 70kg ÷ 2.99
+// BMI = 23.41
+// BMI = 23.4 (to 1 decimal place)
+
+// I need to:
+// 1. Square the height
+// 2. Divide weight by squared height
+// 3. Round the result to 1 decimal place
+// 4. Return the result 
+
+function calculateBMI(weight, height) {
+    const bmi = weight / (height * height);
+    return bmi.toFixed(1);
+}
+
+console.log(calculateBMI(70, 1.73));
+
+
+
+//toFixed(1) tells JavaScript to round the number to 1 decimal place.

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

@@ -14,3 +14,24 @@
 // 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
+
+// NOTES: 
+// "hello there" should become "HELLO_THERE"
+// I need to turn all letters into CAPITALS and replace the space " " with underscore "-"
+
+// From the MDN documentation:
+// I can use the toUpperCase() to turn the tring into all CAPS.
+// I can use the replaceAll() to replace all the spaces with underscores.
+
+// Good function name:
+// toUpperSnakeCase - this name is decriptive and indicates that the function will convert a string to upper snake case.
+
+function toUpperSnakeCase(str) {
+    return str.toUpperCase().replaceAll(" ", "_");
+}
+
+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

@@ -1,6 +1,62 @@
 // In Sprint-1, there is a program written in interpret/to-pounds.js
 
+// ORIGINAL CODE:
+//const penceString = "399p";
+
+//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");
+
+//console.log(`£${pounds}.${pence}`);
+
+
 // You will need to take this code and turn it into a reusable block of code.
 // 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
+// You should call this function a number of times to check it works for different inputs.
+// For example:
+// toPounds("399p") should return "£3.99"
+// toPounds("45p") should return "£0.45"
+// toPounds("9p") should return "£0.09"
+// toPounds("1200p") should return "£12.00"
+
+// The current code removes the "p", makes sur ethe number has at least 3 digits, splits pounds and pences and prints it in money format.
+// Right now, it only works for "399p". I need it to work for "5p" and "1234p".
+// I need to turn it into a function. eg. 'function toPounds(penceString)'. penceString clearly decribes what the input is.
+
+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"));  // £3.99
+console.log(toPounds("45p"));   // £0.45
+console.log(toPounds("9p"));    // £0.09
+console.log(toPounds("1200p")); // £12.00
+