LondonlMay-2025lping wanglCoursework/sprint 2

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

@@ -1,13 +1,13 @@
-// Predict and explain first...
-//  =============> write your prediction here
+"hello Mhairi" === `hello ${mhairiName}`;
+"${mhairiName} is 28" === `Mhairi is ${mhairiAge}`;
 
-// call the function capitalise with a string input
-// interpret the error message and figure out why an error is occurring
+// My answer is:
+const mhairiName = "Mhairi";
+const mhairiAge = 28;
 
-function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
-}
+const sentence1= `Hello ${mhairiName},nice to meet you`;
+console.log(sentence1); // ➜ Output: Hello Mhairi, nice to meet you
 
-// =============> write your explanation here
-// =============> write your new code here
+
+const sentence= `${mhairiName} is ${mhairiAge} years old`;
+console.log(sentence);  // ➜ Output: Mhairi is 28 years old

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

@@ -14,7 +14,22 @@ function convertToPercentage(decimalNumber) {
 
 console.log(decimalNumber);
 
-// =============> write your explanation here
+// =============>const decimalNumber =0.5 is wrong because we can not redeclare parameter using const inside function. 
+// what is more, decimalNumber is not defined in the global scope so we can not use console.log(decimalNumber)
+
 
 // Finally, correct the code to fix the problem
-// =============> write your new code here
+// =============> 
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+console.log(convertToPercentage(0.5)); // Output: "50%"
+
+//or another concised code
+function convertToPercentage(decimalNumber) {
+  return`${decimalNumber * 100}%`;
+}
+
+console.log(convertToPercentage(0.5)); // Output: "50%"

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

@@ -3,18 +3,22 @@
 
 // this function should square any number but instead we're going to get an error
 
-// =============> write your prediction of the error here
+// =============> wrong syntax the number 3 should not be in function
 
 function square(3) {
     return num * num;
 }
 
-// =============> write the error message here
+// =============> syntaxError: Unexpected number
 
-// =============> explain this error message here
+// =============> when defining a function, the parentheses must contain parameter names, not values.
+//                 function square(3) is invalid because 3 is a value, not a parameter name.
 
 // Finally, correct the code to fix the problem
 
-// =============> write your new code here
+// =============>
+function square(num){return num*num};
+
+console.log (square(3));
 
 

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

@@ -1,14 +1,23 @@
 // Predict and explain first...
 
-// =============> write your prediction here
+// =============> console.log(a*b) is inside the function, so it does not return anything instead return undefined by default
 
 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
+// =============> When we call multiply(10, 32) inside the template string, it first runs console.log(320) inside the function.
+// Then it tries to insert the function’s return value (which is undefined) into the string.
+// So, we’ll see:csharp
+//               Copy
+//               Edit
+//               320
+//              The result of multiplying 10 and 32 is undefined
 
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+//  =============> my new code:
+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

@@ -1,5 +1,5 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============> it should be{return a+b;}; rather than have semicolon between return and a+b
 
 function sum(a, b) {
   return;
@@ -8,6 +8,17 @@ function sum(a, b) {
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
-// =============> write your explanation here
+// =============> The return; statement immediately exits the function and returns undefined.
+// The line a + b; after return; never runs — it's unreachable code.So, when we call sum(10, 32), it returns undefined.
+// Output we get:
+// python
+// Copy
+// Edit
+// The sum of 10 and 32 is undefined
 // Finally, correct the code to fix the problem
-//  =============> write your new code here
+//  =============> my new code:
+function sum (a,b) {return a+b;};
+
+console.log (`The sum of 10 and 32 is ${sum(10, 32)}`);
+
+// the output: The sum of 10 and 32 is 42

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

@@ -1,7 +1,7 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// =============> get rid of const num = 103 as it is defined in global scope. the output will be always 3.
 
 const num = 103;
 
@@ -14,11 +14,27 @@ 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
+//num is always 103 inside the function (from the global variable).
+//So, every call to getLastDigit() returns "3" (the last digit of 103).
+//The arguments you pass (like 42, 105) are ignored because the function doesn't take parameters.
+
+
 // Finally, correct the code to fix the problem
-// =============> write your new code here
+// =============> my new code:
+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)}`);
 
+// The output will be: The last digit of 42 is 2
+//                     The last digit of 105 is 5
+//                     The last digit of 806 is 6
 // 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

@@ -14,6 +14,7 @@
 // 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) {
-    // return the BMI of someone based off their weight and height
-}
+function calculateBMI(weight, height) { const bmi= weight/(height*height); return parseFloat(bmi.toFixed(1));}
+
+
+console.log(calculateBMI(58,1.50)); // output: 25.8

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

@@ -14,3 +14,16 @@
 // 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
+
+// The function  to convert any string to UPPER_SNAKE_CASE:
+
+function toUpperSnakeCase(input) {
+  return input.trim().toUpperCase().replace(/\s+/g, "_");}
+
+console.log(toUpperSnakeCase("hello there")); // output:HELLO_THERE
+console.log(toUpperSnakeCase("lord of the rings")); // output: LORD_OF_THE_RINGS
+
+//trim() removes extra spaces at the beginning and end.
+//toUpperCase() makes everything uppercase.
+//replace(/\s+/g, "_") replaces all spaces (even multiple) with underscores.
+

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

@@ -4,3 +4,27 @@
 // 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
+// the code is:
+function formatPenceToPounds(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(formatPenceToPounds("7p"));     // £0.07
+console.log(formatPenceToPounds("67p"));    // £0.67
+console.log(formatPenceToPounds("153p"));   // £1.53
+console.log(formatPenceToPounds("3p"));     // £0.03

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

@@ -17,18 +17,26 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
+// =============> pad is called 3 times — once each for hours, for minutes andvfor 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
+// =============> The first call is for totalHours, and when you call formatTimeDisplay(61), the value of totalHours is:
+//totalHours = (61 - 1) / 60 = 60 / 60 = 1, remainingMinutes = 1
+//totalHours = totalMinutes - remainingMinutes = 1 - 1 = 0
+// So, num = 0 for the first pad call.
 
 // c) What is the return value of pad is called for the first time?
-// =============> write your answer here
+// =============> The return value is "00" because pad(0) results in "00" using .padStart(2, "0").
 
 // 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
+// =============> The last call is for remaining seconds. With input 61, remainingSeconds = 61 % 60 = 1, so num = 1 in the last call.
 
 // 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
+// =============> The return value is "01" – pad(1) returns "01" because it adds a leading zero to make it 2 characters.
+
+// so final output should be "00:01:01"
+
+

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

@@ -23,3 +23,41 @@ console.assert(
   currentOutput2 === targetOutput2,
   `current output: ${currentOutput2}, target output: ${targetOutput2}`
 );
+
+// i put this function for test in console, chrome but it showed undefined then i put 12:00 and the output is:Uncaught SyntaxError: 
+// Unexpected token.so the function is not workable and has some bugs.Unfortunately, i can not work out by myself, i went to chatGpt which 
+// explained the detail to me. function format12HourClock(time) does not work right because it does not work for 12:00, 24:00 d not for
+// minutes either. The right function should be:
+
+function formatAs12HourClock(time) {
+  const hours24 = Number(time.slice(0, 2));
+  const minutes = time.slice(3);
+
+  const period = hours24 >= 12 ? "pm" : "am";
+  const hours12 = hours24 % 12 === 0 ? 12 : hours24 % 12;
+
+  return `${String(hours12).padStart(2, "0")}:${minutes} ${period}`;
+}
+
+const currentOutput = formatAs12HourClock("08:00");
+const targetOutput = "08:00 am";
+console.assert(
+  currentOutput === targetOutput,
+  `current output: ${currentOutput}, target output: ${targetOutput}`
+);
+
+const currentOutput2 = formatAs12HourClock("23:00");
+const targetOutput2 = "11:00 pm";
+console.assert(
+  currentOutput2 === targetOutput2,
+  `current output: ${currentOutput2}, target output: ${targetOutput2}`
+);
+
+// const period = hours24 >= 12 ? "pm" : "am";This line uses a ternary operator — a concise way to write an if...else statement.
+// If hours24 is greater than or equal to 12, then set period to "pm".Otherwise, set it to "am".
+
+// const hours12 = hours24 % 12 === 0 ? 12 : hours24 % 12;This is also a ternary operator (shortcut for if...else) 
+// used to convert 24-hour time to 12-hour time format, which means:"If hours24 % 12 is 0, then set hours12 to 12, 
+// otherwise set it to hours24 % 12." For me, i can understand now with chatgpt help.
+
+