Sprint 2: complete coursework tasks

Author: arunkumarakilan

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

@@ -1,5 +1,9 @@
-// Predict and explain first...
+// Predict and explain first...  
+//Syntax error
 //  =============> write your prediction here
+// We pass str as a parameter to the function.
+//The parameter becomes a local variable inside the function scope.
+//Therefore, we cannot declare another variable with the same name inside the same scope.
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
@@ -10,4 +14,16 @@ function capitalise(str) {
 }
 
 // =============> write your explanation here
+// The parameter str is already a local variable inside the function.
+// Previously, redeclaring it using let caused an error because variables cannot be declared twice in the same scope.
+// Instead of redeclaring it, I modified the existing str variable and returned it.
+// This avoids the redeclaration error and the code runs correctly.
 // =============> write your new code here
+function capitalise(str) {
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return str;
+}
+let str = capitalise("Arun");
+console.log(str);
+
+

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

@@ -1,6 +1,12 @@
 // Predict and explain first...
-
+// syntax error identifier decimalNumber be already declare
+// there is no function call and then you can't use the local variable decimalNumber out of the function
 // Why will an error occur when this program runs?
+//decimalNumber is already declared as a parameter, so declaring it again inside the function causes an error.
+
+//There is no function call.
+
+//You cannot use the local variable decimalNumber outside the function scope.
 // =============> write your prediction here
 
 // Try playing computer with the example to work out what is going on
@@ -11,10 +17,24 @@ function convertToPercentage(decimalNumber) {
 
   return percentage;
 }
-
 console.log(decimalNumber);
 
 // =============> write your explanation here
+//The error occurred because a local variable was redeclared inside the function using a variable keyword. Since the parameter already acts as a local variable, redeclaring it caused an error.
+
+//To fix this, I removed the variable keyword and modified the existing parameter instead.
+
+//I also removed the unused variable from console.log because it was outside the function scope.
 
+//Finally, I called the function directly inside console.log using convertToPercentage() so the function executes properly and returns the correct value.
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  
+  const percentage = `${decimalNumber * 100}%`;
+
+  return percentage;
+}
+
+const decimalNumber = convertToPercentage(0.5) ;
+console.log(decimalNumber);

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

@@ -1,20 +1,44 @@
 
 // Predict and explain first BEFORE you run any code...
 
+// The code has a syntax error because a number is used instead of a parameter name in the function definition.
+// Additionally, num is used inside the function without being declared or passed as an argument, which causes a ReferenceError.
+// If the function is not called, it will not execute.
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
 
+// The code has a syntax error because a number is used instead of a parameter name in the function definition.
+// Additionally, num is used inside the function without being declared or passed as an argument, which causes a ReferenceError.
+// If the function is not called, it will not execute.
+
 function square(3) {
     return num * num;
 }
 
+
+
 // =============> write the error message here
+// syntax error :unexpected number.
 
 // =============> explain this error message here
+// The error occurs because a number is used in the function definition instead of a parameter name. A function definition must contain a parameter (a variable name), not a value.
+
+// Inside the function, num is used but it was never declared or passed as a parameter, which causes a ReferenceError because num is not defined in the scope.
+
+// Also, if the function is not called, it will not execute.
 
 // Finally, correct the code to fix the problem
+// I corrected the function by properly defining num as a parameter instead of using a number in the function definition. This resolved the syntax error.
+
+// Inside the function, num is now defined, so the ReferenceError is fixed.
 
+// I then called the function with an argument and stored the returned value in a variable named num. Although the same variable name is used, the function parameter and the outer variable exist in different scopes, so there is no conflict.
 // =============> write your new code here
 
 
+function square(num) {
+    return num * num;
+}
+let num =  square(3);
+console.log(num);

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

@@ -1,14 +1,39 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// The function multiplies the numbers and prints the answer.
+
+// But it does not return the answer.
+
+// Because there is no return, the function automatically gives back undefined.
+
+// So when we use the function inside the second console.log, the value is undefined.
 
 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 and return are not the same.
+
+// console.log only prints the value to the console.
+
+// It does not send the value back to the function call.
+
+// Because there was no return statement, the function automatically returned undefined.
 
-// Finally, correct the code to fix the problem
+// To fix the issue, I replaced console.log with return.
+
+// By returning a * b, the function now sends the calculated value back to where it was called.
+
+// As a result, the correct value is displayed instead of undefined.
 //  =============> 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

@@ -1,6 +1,9 @@
 // Predict and explain first...
 //  =============> write your prediction here
-
+// The function returns nothing because the return statement has no value. 
+// Once JavaScript reaches return, the function stops executing. 
+// Therefore, the line after it is dead code and never runs. 
+// Since the function does not return a value, it returns undefined, which is why the template string displays undefined.
 function sum(a, b) {
   return;
   a + b;
@@ -9,5 +12,14 @@ function sum(a, b) {
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// The function now correctly returns the result of a + b. 
+// Since the addition is included in the return statement, the function sends back the calculated value. 
+// Therefore, when the function is called inside the template string, it displays the correct result, 42.
 // 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

@@ -2,6 +2,11 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// The output will be 3 for every function call. 
+// This is because the function does not have a parameter, so it ignores the values passed in the function calls. 
+// Instead, it uses the global variable num, which is set to 103. 
+// The last digit of 103 is 3, so the function always returns 3.
+// variable num inside function take the input from the global variable num in the outside of the function
 
 const num = 103;
 
@@ -15,10 +20,42 @@ 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 have a parameter.
+// Even though values like 42, 105, and 806 are passed when calling the function, they are ignored.
+
+// Inside the function, the variable num refers to the global variable num, which is set to 103.
+
+// Each time the function runs, it converts 103 to a string and extracts the last character using slice(-1).
+
+// The last digit of 103 is "3".
+
+// Therefore, every function call returns "3".
 // Finally, correct the code to fix the problem
 // =============> write your new code here
 
+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
+// In the previous version, the function was not working properly because it used a global variable instead of a parameter. 
+// Since the function did not define a parameter, it ignored the values passed during the function calls and always used the same global value.
+
+// In the corrected version, the global variable was removed and a parameter num was added to the function definition. 
+// Now, the function receives the argument passed during each function call and correctly returns the last digit of that number.
+
+// Therefore, the output becomes:
+
+// The last digit of 42 is 2
+// The last digit of 105 is 5
+// The last digit of 806 is 6

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

@@ -15,5 +15,9 @@
 // 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);
+    bmi = bmi.toFixed(1);
+    return Number(bmi);
+
+}
+ console.log(calculateBMI(62 , 1.8));

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 upperSnakeCase(str){
+    str = str.toUpperCase()
+
+  return str.replaceAll(" " , "_");
+;
+
+}
+console.log(upperSnakeCase("hello there"));
+console.log(upperSnakeCase("lord of the rings"));

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

@@ -4,3 +4,22 @@
 // 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("10p"));
+ console.log(toPounds("5p"));

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

@@ -8,27 +8,36 @@ function formatTimeDisplay(seconds) {
   const remainingMinutes = totalMinutes % 60;
   const totalHours = (totalMinutes - remainingMinutes) / 60;
 
-  return `${pad(totalHours)}:${pad(remainingMinutes)}:${pad(remainingSeconds)}`;
+  return  `${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
+console.log(formatTimeDisplay(61))
+
+// You will need to play computer with this example - use the Python Visualizer 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
-
-// Call formatTimeDisplay with an input of 61, now answer the following:
+// ans: 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
-
-// c) What is the return value of pad is called for the first time?
-// =============> write your answer here
+// =============> write your answer here  : 0
+// c) What is the return value of pad is called for the first time? 
+// =============> write your answer here value : 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
-
+// =============> write your answer here : 1 When formatTimeDisplay(61) is called, the value 61 is passed as the argument to seconds.
+// Then remainingSeconds is calculated using seconds % 60, which gives 1.
+// The last call to pad is pad(remainingSeconds).
+// Since remainingSeconds is 1, the value assigned to num in the last call 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
+// =============> write your answer here : 01 When formatTimeDisplay(61) is called, the value 1 is passed to pad during the last call because remainingSeconds equals 1.
+// Inside the pad function:
+// The number 1 is converted to a string.
+// padStart(2, "0") ensures the string has at least two characters.
+// Since "1" has only one character, a "0" is added to the beginning.
+// So "1" becomes "01".
+// This ensures the time format follows the 00:00:00 structure.