Barcelona | OCT-25 | Tatiana Kuzmina | Sprint 2 | Module-Structuring-and-Testing-Data

Sprint-1/1-key-exercises/1-count.js

@@ -4,3 +4,6 @@ count = count + 1;
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
 // Describe what line 3 is doing, in particular focus on what = is doing
+//Answer:
+// Line 3 takes the current value of `count`, adds 1, and assigns the result back to `count`.
+// The = operator is the assignment operator.

Sprint-1/1-key-exercises/2-initials.js

@@ -5,7 +5,9 @@ let lastName = "Johnson";
 // Declare a variable called initials that stores the first character of each string.
 // This should produce the string "CKJ", but you must not write the characters C, K, or J in the code of your solution.
 
-let initials = ``;
-
+let initials = firstName[0] + middleName[0] + lastName[0];
+console.log(initials)
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 
+// The variable 'initials' takes the first character of firstName, middleName, and lastName, 
+// and combines them to form a new string.

Sprint-1/1-key-exercises/3-paths.js

@@ -17,7 +17,8 @@ console.log(`The base part of ${filePath} is ${base}`);
 // Create a variable to store the dir part of the filePath variable
 // Create a variable to store the ext part of the variable
 
-const dir = ;
-const ext = ;
+const dir = filePath.slice(0, lastSlashIndex);
+const lastDotIndex = base.lastIndexOf(".");
+const ext = base.slice(lastDotIndex);
 
 // https://www.google.com/search?q=slice+mdn

Sprint-1/1-key-exercises/4-random.js

@@ -7,3 +7,9 @@ const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 // Try breaking down the expression and using documentation to explain what it means
 // It will help to think about the order in which expressions are evaluated
 // Try logging the value of num and running the program several times to build an idea of what the program is doing
+//Answer:
+// The variable 'num' stores a random integer between 'minimum' (1) and 'maximum' (100), inclusive.
+// Math.random() generates a random number from 0 up to (but not including) 1.
+// Multiplying by (maximum - minimum + 1) scales it to the desired range.
+// Math.floor() rounds down to the nearest whole number.
+// Adding 'minimum' shifts the range so it starts at 1 instead of 0.

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

@@ -1,2 +1,2 @@
-This is just an instruction for the first activity - but it is just for human consumption
-We don't want the computer to run these 2 lines - how can we solve this problem?
+//This is just an instruction for the first activity - but it is just for human consumption
+//We don't want the computer to run these 2 lines - how can we solve this problem?

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

@@ -1,4 +1,9 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+console.log(age); 
+
+// We use 'let' to create a variable that can be reassigned.
+// 'age' starts at 33, then we add 1 to it and store the result back in 'age'.
+// console.log(age) outputs 34.

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

@@ -1,5 +1,9 @@
 // Currently trying to print the string "I was born in Bolton" but it isn't working...
 // what's the error ?
 
-console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+
+// The error was that the variable 'cityOfBirth' was used before it was declared.
+// Using 'const', a variable must be declared before it can be accessed.
+// Correct order: first declare the variable, then use it in console.log.

Sprint-1/2-mandatory-errors/3.js

@@ -1,5 +1,6 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(last4Digits);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working

Sprint-1/2-mandatory-errors/4.js

@@ -1,2 +1,8 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const hour12ClockTime = "20:53";
+const hour24ClockTime = "08:53";
+
+console.log(hour12ClockTime);
+console.log(hour24ClockTime);
+
+// Variable names cannot start with a number, so I use hour12ClockTime and hour24ClockTime.
+// This way the code works and prints the correct times.

Sprint-1/3-mandatory-interpret/1-percentage-change.js

@@ -2,7 +2,7 @@ let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -20,3 +20,26 @@ console.log(`The percentage change is ${percentageChange}`);
 // d) Identify all the lines that are variable declarations
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+
+//Answer:
+// a) Function calls are on these lines:
+// carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+// console.log(`The percentage change is ${percentageChange}`);
+
+// b) Error occurs on the line:
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// Reason: missing comma between arguments of replaceAll. Fix: replaceAll(",", "")
+
+// c) Variable reassignment lines:
+// carPrice = Number(carPrice.replaceAll(",", ""));
+// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
+// d) Variable declaration lines:
+// let carPrice = "10,000";
+// let priceAfterOneYear = "8,543";
+// const priceDifference = carPrice - priceAfterOneYear;
+// const percentageChange = (priceDifference / carPrice) * 100;
+
+// e) Number(carPrice.replaceAll(",", "")) removes all commas from the string and converts it to a number so calculations can be done.

Sprint-1/3-mandatory-interpret/2-time-format.js

@@ -23,3 +23,18 @@ console.log(result);
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+//Answer:
+// a) Variable declarations:
+// movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours, result (6 in total)
+
+// b) Function calls:
+// console.log(result) (1 function call)
+
+// c) movieLength % 60 gives the remainder when movieLength is divided by 60, representing the remaining seconds after full minutes are counted
+
+// d) totalMinutes = (movieLength - remainingSeconds) / 60 calculates the total number of full minutes by removing leftover seconds and dividing by 60
+
+// e) result represents the movie duration in hours:minutes:seconds format. A better name could be formattedMovieLength or movieTimeString
+
+// f) The code works for any positive number of seconds, but single-digit minutes or seconds will not have leading zeros. To fix this, use padStart to format as hh:mm:ss

Sprint-1/3-mandatory-interpret/3-to-pounds.js

@@ -1,21 +1,27 @@
 const penceString = "399p";
+//    Initialize a string variable with the value "399p"
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
   penceString.length - 1
 );
-
+//Remove the trailing "p" from the string to get just the number part, e.g. "399"
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//    Ensure the string has at least 3 characters by adding leading zeros if needed, e.g. "399" stays "399", "5" becomes "005"
+
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
+//    Take all but the last two characters to get the pounds part, e.g. "3" from "399"
 
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
+//    Take the last two characters for the pence part. If less than 2 characters, add a zero at the end, e.g. "99" from "399"
 
 console.log(`£${pounds}.${pence}`);
+//    Combine pounds and pence into a formatted string and print, e.g. "£3.99"
 
 // This program takes a string representing a price in pence
 // The program then builds up a string representing the price in pounds

Sprint-1/4-stretch-explore/chrome.md

@@ -16,3 +16,12 @@ Now try invoking the function `prompt` with a string input of `"What is your nam
 
 What effect does calling the `prompt` function have?
 What is the return value of `prompt`?
+
+Answer:
+Calling alert("Hello world!") shows a popup with the message "Hello world!" to the user.
+The alert function does not return any value (returns undefined).
+Calling prompt("What is your name?") shows a popup with a text input field asking the user for their name.
+The return value of prompt is the text entered by the user, or null if the user presses Cancel.
+Example:
+const myName = prompt("What is your name?");
+console.log(myName); // will display the name entered or null

Sprint-1/4-stretch-explore/objects.md

@@ -14,3 +14,13 @@ Answer the following questions:
 
 What does `console` store?
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+
+
+Answer:
+1. console stores an object that contains methods for logging and debugging, such as log, warn, error, assert, etc.
+2. typeof console returns "object", confirming that console is an object.
+3. console.log or console.assert uses the dot (.) syntax to access a method (function) of the console object.
+The dot means "this method belongs to this object".
+4. Example:
+console.log("Hello"); // calls the log method of the console object
+console.assert(1 === 2, "Not equal!"); // calls the assert method of the console object

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

@@ -10,4 +10,14 @@ function capitalise(str) {
 }
 
 // =============> write your explanation here
+// The error occurs because the function expects a string argument.
+// If no argument is passed, str is undefined, and accessing str[0]
+// causes a TypeError since undefined has no properties.
 // =============> write your new code here
+function capitalise(str) {
+  if (typeof str !== "string" || str.length === 0) {
+    return "";
+  }
+
+  return `${str[0].toUpperCase()}${str.slice(1)}`;
+}

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

@@ -2,6 +2,9 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// I predict there will be a SyntaxError or ReferenceError because
+// the variable `decimalNumber` is declared twice: once as a parameter
+// and once with `const` inside the function.
 
 // Try playing computer with the example to work out what is going on
 
@@ -15,6 +18,18 @@ function convertToPercentage(decimalNumber) {
 console.log(decimalNumber);
 
 // =============> write your explanation here
+// The error occurs because we are trying to declare a new constant `decimalNumber`
+// inside the function that has the same name as the function parameter.
+// In addition, `console.log(decimalNumber)` is outside the function scope,
+// so decimalNumber is not defined there.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  // Remove redeclaration, use the parameter directly
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+// Example usage:
+console.log(convertToPercentage(0.5)); // "50%"

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

@@ -4,17 +4,28 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+// I predict there will be a SyntaxError because you cannot put a number (3) 
+// directly in the parentheses of a function definition. 
+// Function parameters must be valid variable names.
 
 function square(3) {
     return num * num;
 }
 
 // =============> write the error message here
+// SyntaxError: Unexpected number
 
 // =============> explain this error message here
+// The error occurs because the function parameter is incorrectly written as a literal number (3). 
+// JavaScript expects a variable name to use as the parameter, not a value.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
+function square(num) {
+    return num * num;
+}
 
+// Example usage:
+console.log(square(3)); // 9
 

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

@@ -1,6 +1,8 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// I predict that the output will be "The result of multiplying 10 and 32 is undefined"
+// because the multiply function does not return a value, it only logs it to the console.
 
 function multiply(a, b) {
   console.log(a * b);
@@ -9,6 +11,15 @@ function multiply(a, b) {
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
 // =============> write your explanation here
+// The function multiply prints the product of a and b using console.log,
+// but it does not return any value. In JavaScript, if a function does not
+// return anything, it implicitly returns undefined. Therefore, when we
+// try to use multiply(10, 32) inside the template literal, it 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)}`); // 320

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

@@ -1,5 +1,7 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// I predict that the output will be "The sum of 10 and 32 is undefined"
+// because the function has a `return` statement with no value before the expression `a + b`.
 
 function sum(a, b) {
   return;
@@ -9,5 +11,13 @@ function sum(a, b) {
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// The function returns immediately at the `return;` statement without a value.
+// The next line `a + b` is never executed. Therefore, the function returns undefined.
+
 // 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)}`); // "42"

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

@@ -2,7 +2,11 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// I predict that all three console.log statements will return "3"
+// because the function getLastDigit always uses the constant num = 103
+// and ignores any arguments passed to it.
 
+// Original code
 const num = 103;
 
 function getLastDigit() {
@@ -15,10 +19,23 @@ 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
+// The output is:
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
+
 // =============> write your explanation here
+// The function getLastDigit does not accept any parameter,
+// so it always uses the global constant num = 103.
+// Therefore, no matter what number we try to pass, it always returns '3'.
+// The arguments (42, 105, 806) are ignored.
+
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function getLastDigit(number) {
+  return number.toString().slice(-1);
+}
 
-// This program should tell the user the last digit of each number.
-// Explain why getLastDigit is not working properly - correct the problem
+console.log(`The last digit of 42 is ${getLastDigit(42)}`); // 2
+console.log(`The last digit of 105 is ${getLastDigit(105)}`); // 5
+console.log(`The last digit of 806 is ${getLastDigit(806)}`); // 6

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

@@ -15,5 +15,11 @@
 // 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));
+}
+
+// Check
+console.log(calculateBMI(70, 1.73)); // 23.4
+console.log(calculateBMI(80, 1.8)); // 24.7
+console.log(calculateBMI(60, 1.6)); // 23.4

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

@@ -14,3 +14,11 @@
 // 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.replace(/ /g, "_").toUpperCase();
+}
+
+// Check
+console.log(toUpperSnakeCase("hello there")); // HELLO_THERE
+console.log(toUpperSnakeCase("lord of the rings")); // LORD_OF_THE_RINGS
+console.log(toUpperSnakeCase("my variable name")); // MY_VARIABLE_NAME