London | 26-ITP-May | Bisrat Tesfay | Sprint 2 | Coursework/sprint 2

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

@@ -1,6 +1,6 @@
 // Predict and explain first...
 //  =============> write your prediction here
-
+// I predict the code will give an error because inside the function we create a variable called str again.
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
@@ -9,5 +9,10 @@ function capitalise(str) {
   return str;
 }
 
+console.log(capitalise("hello"));
 // =============> write your explanation here
+// The error occurs because we are trying to declare a variable named str inside the function, but it is already declared as a parameter. This creates a conflict and results in a syntax error.
 // =============> write your new code here
+function capitalise(str) {
+  return `${str[0].toUpperCase()}${str.slice(1)}`;
+}

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

@@ -2,7 +2,7 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
-
+// console.log(decimalNumber); will cause error because decimalNumber only exists inside the function.
 // Try playing computer with the example to work out what is going on
 
 function convertToPercentage(decimalNumber) {
@@ -15,6 +15,14 @@ function convertToPercentage(decimalNumber) {
 console.log(decimalNumber);
 
 // =============> write your explanation here
-
+//The error happens because the function already has a parameter called decimalNumber.
+//Creating another variable with the same name inside the function causes a conflict
 // 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

@@ -4,17 +4,26 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+// it is syntax error. 3 is a value not a variable name.
 
 function square(3) {
     return num * num;
 }
 
 // =============> write the error message here
+//function square(3) {
+                ^
 
+//SyntaxError: Unexpected number
 // =============> explain this error message here
+//The error is as I predicted. The function parameter should be a variable name, not a value. 
+//In this case, 3 is a value and cannot be used as a parameter name.
 
 // 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 +1,7 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// I predict the code will give an error because the multiply function does not return a value.
 
 function multiply(a, b) {
   console.log(a * b);
@@ -9,6 +10,16 @@ function multiply(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 but does not return anything.
+// The function multiply(a, b) prints the result using console.log(a * b), but it does not return a value. When multiply(10, 32) is called inside the template literal, it first prints 320 to the console. Then, because the function has no return statement, it returns undefined. As a result, the second console.log prints:
 
+//The result of multiplying 10 and 32 is undefined
+
+//This happens because console.log() only displays a value on the screen, while return sends a value back to where the function was called
 // 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

@@ -1,6 +1,6 @@
 // Predict and explain first...
 //  =============> write your prediction here
-
+// I predict the code will give an error because the sum function does not return a value.
 function sum(a, b) {
   return;
   a + b;
@@ -9,5 +9,12 @@ function sum(a, b) {
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// The function sum(a, b) has a return statement that does not return the result of a + b.
+// Instead, it returns undefined because the return statement is followed by a semicolon, which ends the statement before the addition operation is 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

@@ -2,6 +2,7 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+//The function has no parameter, so it cannot use input values like 42, 105, 806
 
 const num = 103;
 
@@ -15,10 +16,21 @@ 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 out will be the last digit of 103 for all three console.log statements, because the function getLastDigit() is using the variable num which is set to 103, instead of using the input values passed to it.
 // Explain why the output is the way it is
 // =============> write your explanation here
+//The function is not using the value passed into it.
 // 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
+// If a function should work with different values → it must have parameters.
+// Otherwise it will always use the same fixed value

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
-}
+  // return the BMI of someone based off their weight and height
+  const bmi = weight / (height * height);
+  return Number(bmi.toFixed(1));
+}
+console.log(calculateBMI(72, 1.76));
+// just to check the function is working correctly, and it works.

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

@@ -14,3 +14,9 @@
 // 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.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 +4,26 @@
 // 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("123p"));
+console.log(toPounds("5p"));
+console.log(toPounds("0p"));

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

@@ -22,17 +22,22 @@ function formatTimeDisplay(seconds) {
 
 // a) When formatTimeDisplay is called how many times will pad be called?
 // =============> write your answer here
+// three times- hours, minutes, seconds
 
 // 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
+// num = 0, because totalHours = 0
 
 // c) What is the return value of pad is called for the first time?
 // =============> write your answer here
+// "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
+//  num = 1, because remainingSeconds = 1.
 
 // e) What is the return value of pad when it is called for the last time in this program?  Explain your answer
 // =============> write your answer here
+// "01", because the function adds a leading zero to the single-digit number 1, resulting in the string "01".

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

@@ -23,3 +23,51 @@ console.assert(
   currentOutput2 === targetOutput2,
   `current output: ${currentOutput2}, target output: ${targetOutput2}`
 );
+
+const currentOutput3 = formatAs12HourClock("00:00");
+const targetOutput3 = "12:00 am";
+console.assert(
+  currentOutput3 === targetOutput3,
+  `current output: ${currentOutput3}, target output: ${targetOutput3}`
+);
+
+const currentOutput4 = formatAs12HourClock("12:00");
+const targetOutput4 = "12:00 pm";
+console.assert(
+  currentOutput4 === targetOutput4,
+  `current output: ${currentOutput4}, target output: ${targetOutput4}`
+);
+
+const currentOutput5 = formatAs12HourClock("14:30");
+const targetOutput5 = "2:30 pm";
+console.assert(
+  currentOutput5 === targetOutput5,
+  `current output: ${currentOutput5}, target output: ${targetOutput5}`
+);
+
+console.log(formatAs12HourClock("08:00"));
+console.log(formatAs12HourClock("23:00"));
+console.log(formatAs12HourClock("00:00"));
+console.log(formatAs12HourClock("12:00"));
+console.log(formatAs12HourClock("14:30"));
+
+//The function did not handle the edge cases 00:00 and 12:00.
+// The correct function should be like this
+function formatAs12HourClock(time) {
+  const hours = Number(time.slice(0, 2));
+  const minutes = time.slice(2);
+
+  if (hours === 0) {
+    return `12${minutes} am`;
+  }
+
+  if (hours === 12) {
+    return `12${minutes} pm`;
+  }
+
+  if (hours > 12) {
+    return `${hours - 12}${minutes} pm`;
+  }
+
+  return `${time} am`;
+}