diff --git a/Sprint-1/1-key-exercises/1-count.js b/Sprint-1/1-key-exercises/1-count.js index 117bcb2b6..4b32be4ff 100644 --- a/Sprint-1/1-key-exercises/1-count.js +++ b/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 + +// The = operator assigns a new value to 'count'. It takes the current value of 'count'. +// adds 1 to it, and then stores that new value back into the 'count' variable. \ No newline at end of file diff --git a/Sprint-1/1-key-exercises/2-initials.js b/Sprint-1/1-key-exercises/2-initials.js index 47561f617..7905601df 100644 --- a/Sprint-1/1-key-exercises/2-initials.js +++ b/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 = ``; - -// https://www.google.com/search?q=get+first+character+of+string+mdn +// + joins them in one string +// [0] gets the first character of each string +let initials = firstName[0] + middleName[0] +lastName[0]; +console.log(initials); // "CKJ" +// https://www.google.com/search?q=get+first+character+of+string+mdn \ No newline at end of file diff --git a/Sprint-1/1-key-exercises/3-paths.js b/Sprint-1/1-key-exercises/3-paths.js index ab90ebb28..519df28c2 100644 --- a/Sprint-1/1-key-exercises/3-paths.js +++ b/Sprint-1/1-key-exercises/3-paths.js @@ -17,7 +17,7 @@ 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 ext = base.slice(base.lastIndexOf(".") + 1); // https://www.google.com/search?q=slice+mdn \ No newline at end of file diff --git a/Sprint-1/1-key-exercises/4-random.js b/Sprint-1/1-key-exercises/4-random.js index 292f83aab..279d16980 100644 --- a/Sprint-1/1-key-exercises/4-random.js +++ b/Sprint-1/1-key-exercises/4-random.js @@ -1,9 +1,26 @@ const minimum = 1; const maximum = 100; -const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum; +const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum; // Generates a random whole number between minimum and maximum // In this exercise, you will need to work out what num represents? // 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 + +// Generate a random decimal number between 0 and 1 +const decimal = Math.random(); +// Calculate the range size +const range = maximum - minimum + 1; +// Scale the decimal to the range +const scaled = decimal * range; +// Round down to get a whole number +const floored = Math.floor(scaled); +// Shift the number up to start at the minimum +const result = floored + minimum; +// Log each part to understand the process +console.log("decimal:", decimal); +console.log("range:", range); +console.log("scaled:", scaled); +console.log("floored:", floored); +console.log("result:", result); \ No newline at end of file diff --git a/Sprint-1/2-mandatory-errors/0.js b/Sprint-1/2-mandatory-errors/0.js index cf6c5039f..6a7a7f690 100644 --- a/Sprint-1/2-mandatory-errors/0.js +++ b/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? \ No newline at end of file +// 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? \ No newline at end of file diff --git a/Sprint-1/2-mandatory-errors/1.js b/Sprint-1/2-mandatory-errors/1.js index 7a43cbea7..99b906fc2 100644 --- a/Sprint-1/2-mandatory-errors/1.js +++ b/Sprint-1/2-mandatory-errors/1.js @@ -1,4 +1,6 @@ // trying to create an age variable and then reassign the value by 1 -const age = 33; +// let allows reassignment whereas const does not +let age = 33; age = age + 1; +console.log(age); \ No newline at end of file diff --git a/Sprint-1/2-mandatory-errors/2.js b/Sprint-1/2-mandatory-errors/2.js index e09b89831..f30f6835a 100644 --- a/Sprint-1/2-mandatory-errors/2.js +++ b/Sprint-1/2-mandatory-errors/2.js @@ -3,3 +3,11 @@ console.log(`I was born in ${cityOfBirth}`); const cityOfBirth = "Bolton"; + +// The error is that the variable cityOfBirth is used before it is declared and assigned a value. +// To fix the error, we need to declare and assign a value to cityOfBirth before using it in the console.log statement. + +/* Corrected code: +const cityOfBirth = "Bolton"; +console.log(`I was born in ${cityOfBirth}`); +*/ \ No newline at end of file diff --git a/Sprint-1/2-mandatory-errors/3.js b/Sprint-1/2-mandatory-errors/3.js index ec101884d..3ecdd332f 100644 --- a/Sprint-1/2-mandatory-errors/3.js +++ b/Sprint-1/2-mandatory-errors/3.js @@ -1,5 +1,11 @@ +// Prediction: The code will not work because cardNumber is defined as a number not a string. +// The slice method is a string and arrays method, and cannot be used on a number type. +// Error: TypeError: cardNumber.slice is not a function + const cardNumber = 4533787178994213; -const last4Digits = cardNumber.slice(-4); +const last4Digits = cardNumber.toString().slice(-4); + +console.log(last4Digits); // Should output: 4213 // The last4Digits variable should store the last 4 digits of cardNumber // However, the code isn't working diff --git a/Sprint-1/2-mandatory-errors/4.js b/Sprint-1/2-mandatory-errors/4.js index 21dad8c5d..1f6ed10fa 100644 --- a/Sprint-1/2-mandatory-errors/4.js +++ b/Sprint-1/2-mandatory-errors/4.js @@ -1,2 +1,8 @@ -const 12HourClockTime = "20:53"; -const 24hourClockTime = "08:53"; \ No newline at end of file +// Prediction: The code will fail because variable names cannot start with a number. +// JavaScript identifiers must begin with a letter, $, or _. Starting with a 12 or 24 is invalid. +// The quotes used are also smart quotes which will cause a syntax error. + +// Corrected code: + +const twelveHourClockTime = "20:53"; +const twentyFourHourClockTime = "08:53"; \ No newline at end of file diff --git a/Sprint-1/3-mandatory-interpret/1-percentage-change.js b/Sprint-1/3-mandatory-interpret/1-percentage-change.js index e24ecb8e1..e2a9abad6 100644 --- a/Sprint-1/3-mandatory-interpret/1-percentage-change.js +++ b/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; @@ -12,11 +12,37 @@ console.log(`The percentage change is ${percentageChange}`); // Read the code and then answer the questions below // a) How many function calls are there in this file? Write down all the lines where a function call is made +// carPrice.replaceAll(",", "") - line 4 +// Number(...) - line 4, wraps the result of replaceAll +// priceAfterOneYear.replaceAll("," "") - line 5 +// Number(...) - line 5, wraps the second result of replaceAll +// console.log(..) - line 9 +// Answer: There are 5 function calls in total, on lines 4, 5 and 9. // b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem? +// Error: priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," "")); +// Answer: +// The red line on replaceAll("," "") indicates that there is a syntax error on line 5, as shown in the code. +// A comma was missing between the two arguments inside the replaceAll function call. +// To fix this, add a comma between the two arguments like this: replaceAll(",", ""). + +// Error: SyntaxError: missing ) after argument list and price AfterOneYear = Number(priceAfterOneYear.replaceAll("," "")); +// The error appears on the console.log line because the string was written using smart quotes instead of normal JavaScript quotes. +// Smart quotes break the strong syntax rules of JavaScript. +// To fix this, replace the smart quotes with straight quotes. // c) Identify all the lines that are variable reassignment statements +// carPrice = Number(carPrice.replaceAll(",", "")); +// priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", "")); +// Answer: Lines 4 and 5 are variable reassignment statements. // d) Identify all the lines that are variable declarations +// let carPrice = "10,000"; +// let priceAfterOneYear = "8,543"; +// const priceDifference = carPrice - priceAfterOneYear; +// const percentageChange = (priceDifference / carPrice) * 100; +// Answer: Lines 1, 2, 7 and 8 are variable declarations. // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression? +// The expression Number(carPrice.replaceAll(",", "")) is removing all the commas from carPrice string by replacing every comma with an empty string. +// The purpose is to clean the value so that it can be converted to a proper number using Number(). \ No newline at end of file diff --git a/Sprint-1/3-mandatory-interpret/2-time-format.js b/Sprint-1/3-mandatory-interpret/2-time-format.js index 47d239558..748ebd1fa 100644 --- a/Sprint-1/3-mandatory-interpret/2-time-format.js +++ b/Sprint-1/3-mandatory-interpret/2-time-format.js @@ -12,14 +12,33 @@ console.log(result); // For the piece of code above, read the code and then answer the following questions // a) How many variable declarations are there in this program? +// movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours, result +// Answer: Each uses const, so each counts as a declaration. There are 6 variable declarations in total. // b) How many function calls are there? +// console.log(result) +// Answer: There is 1 function call in this program. Everything else is arithmetic, not a function call. // c) Using documentation, explain what the expression movieLength % 60 represents // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators +// According to the documentation, the remainder operator (%) returns the remainder after dividing one number by another. +// In this case, movieLength % 60 divides movieLength (which is in seconds) by 60, +// returns the leftover seconds that don't fit into a full minute. // d) Interpret line 4, what does the expression assigned to totalMinutes mean? +// This line removes the leftover seconds (remainingSeconds) and converts the remaining whole seconds into minutes. +// So it gives you the total number of whole minutes in the movie. // e) What do you think the variable result represents? Can you think of a better name for this variable? +// The result variable represents the final formatted time of the movie in hours, minutes and seconds. +// hours:minutes:seconds format. A better name could be formattedTime or movieDuration. // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer +// If I set movieLength to 8784, the output will be "2:26:24", which is correct, +// so this is a normal case where the code works as expected. + +// If I set movieLength to 0, the output will be "0:0:0", which is also correct, +// shows it can handle edge cases even though it is an unusual value. + +// If I set movieLength to -200, the output will be "-1:-3:-20", which is not a valid time format, +// shows that the logic breaks because the code does not protect against invalid negative inputs. diff --git a/Sprint-1/3-mandatory-interpret/3-to-pounds.js b/Sprint-1/3-mandatory-interpret/3-to-pounds.js index 60c9ace69..ad756688d 100644 --- a/Sprint-1/3-mandatory-interpret/3-to-pounds.js +++ b/Sprint-1/3-mandatory-interpret/3-to-pounds.js @@ -25,3 +25,28 @@ console.log(`£${pounds}.${pence}`); // To begin, we can start with // 1. const penceString = "399p": initialises a string variable with the value "399p" + +// 2. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1): +// Removes the final "p" character so only the numeric part of the price remains + +// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"): +// Ensures the number is atleast 3 digits long by adding leading zeros when necessary, which helps with consistent formatting + +// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2): +// Extracts everything except the last two digits to form the pounds portion of the price + +// 5. const pence = paddedPenceNumberString .substring(paddedPenceNumberString.length - 2) .padEnd(2, "0"): +// Takes the final two digits of the padded string to form the pence portion + +// 6. console.log(`£${pounds}.${pence}`): +// Combines the pounds and pence into a standard currency format and prints it to the console, "£3.99" + +// Test cases to consider: +// "5p" should output "£0.05" +// "99p" shsould output "£0.99" +// "399p" should output "£3.99" +// "0p" should output "£0.00" +// "1000p" should output "£10.00" + +// The program takes a string representing a price in pence (e.g., "399p") +// and converts it to a string representing the price in pounds (e.g., "£3.99"). \ No newline at end of file diff --git a/Sprint-1/4-stretch-explore/chrome.md b/Sprint-1/4-stretch-explore/chrome.md index e7dd5feaf..7d7adf34f 100644 --- a/Sprint-1/4-stretch-explore/chrome.md +++ b/Sprint-1/4-stretch-explore/chrome.md @@ -11,8 +11,12 @@ In the Chrome console, invoke the function `alert` with an input string of `"Hello world!"`; What effect does calling the `alert` function have? +- Shows a message in a pop up box and stops the page until the user clicks OK. Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`. What effect does calling the `prompt` function have? +- Shows a pop up box with a message and an input box. + What is the return value of `prompt`? +- Prompt() returns the text the user enters, or null if they cancel the dialog. \ No newline at end of file diff --git a/Sprint-1/4-stretch-explore/objects.md b/Sprint-1/4-stretch-explore/objects.md index 0216dee56..2d9d68c3b 100644 --- a/Sprint-1/4-stretch-explore/objects.md +++ b/Sprint-1/4-stretch-explore/objects.md @@ -5,12 +5,19 @@ In this activity, we'll explore some additional concepts that you'll encounter i Open the Chrome devtools Console, type in `console.log` and then hit enter What output do you get? +- ƒ log() { [native code] } Now enter just `console` in the Console, what output do you get back? +- console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …} Try also entering `typeof console` +- 'object' Answer the following questions: What does `console` store? +- The console stores a history of messages your code prints while it runs. + What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean? +- You are accessing a function (a method) that belongs to the console object. +- The `.` is used to access that method from the object. \ No newline at end of file