update to all files sprint-2 key-exercises, mandatory errors and mandatory-interpret folders

Author: Mugs3

Sprint-2a/1-key-exercises/1-count.js

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+let count = 0;
+
+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: The = means assignment. The value of count is 0 but it increments by 1

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

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+const firstName = "Creola";
+const middleName = "Katherine";
+const lastName = "Johnson";
+// const initial = "initials";
+// const index = 1;
+
+// console.log('The ${Initial} ${index} is ${firstName.charAt(index)}');
+// 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.
+
+const initials = firstName[0] + middleName[0] + lastName[0];
+console.log(initials);
+
+// https://www.google.com/search?q=get+first+character+of+string+mdn

Sprint-2a/1-key-exercises/3-paths.js

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+// The diagram below shows the different names for parts of a file path on a Unix operating system
+
+// ┌─────────────────────┬────────────┐
+// │          dir        │    base    │
+// ├──────┬              ├──────┬─────┤
+// │ root │              │ name │ ext │
+// "  /    home/user/dir / file  .txt "
+// └──────┴──────────────┴──────┴─────┘
+
+// (All spaces in the "" line should be ignored. They are purely for formatting.)
+
+const filePath = "/Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt";
+const lastSlashIndex = filePath.lastIndexOf("/");
+const base = filePath.slice(lastSlashIndex + 1);
+console.log(`The base part of ${filePath} is ${base}`);
+// console.log('The dir path of ${dir} is ${filePath}.${lastSlashIndex}'); 
+
+
+// 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 = filePath.slice(0, lastSlashIndex);
+const ext = base.slice(base.lastIndexOf("."));
+
+console.log(`The dir part of ${filePath} is ${dir}`);
+console.log(`The ext part of ${base} is ${ext}`);
+
+// https://www.google.com/search?q=slice+mdn

Sprint-2a/1-key-exercises/4-random.js

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+const minimum = 1;
+const maximum = 100;
+
+const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+// (0.68 * 100 ) + 1
+console.log(num)
+
+// 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
+
+// Answer: For calculations i utilised BODMAS formula solving numbers in brackets first, multiplication, subtraction and addition
+// I used 0.68 for math.floor(random number) + 1
+// Sum = 69

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

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+//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?
+
+// I have commented out the lines. The computer removes commented lines from code compilation

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

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+// trying to create an age variable and then reassign the value by 1
+
+let age = 33;
+age = age + 1;
+
+console.log(age)
+
+// The TypeError: Assignment to constant variable implies we are trying to reassign the variable twice.
+// This case, I have used let instead in order to allow the variable to be reused.

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

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+// Currently trying to print the string "I was born in Bolton" but it isn't working...
+// what's the error ?
+
+const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+
+
+// The error is ReferenceError: Cannot access 'cityOfBirth' before initialization
+// Answer: I switched the order by declaring the const first before calling /printing 

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

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+const cardNumber = 4533787178994213;
+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
+// Before running the code, make and explain a prediction about why the code won't work
+// Then run the code and see what error it gives.
+// Consider: Why does it give this error? Is this what I predicted? If not, what's different?
+// Then try updating the expression last4Digits is assigned to, in order to get the correct value
+
+//Prediction was the code would run successfully without error although with the wrong results due to absence of syntax errors in the file
+// Error returned: TypeError: cardNumber.slice is not a function
+// Lesson learnt here; slice method is only available for strings or arrays not numbers
+// So converted the cardNumber into a string first

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

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+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";
+console.log(twelveHourClockTime);
+console.log(twentyFourHourClockTime);
+
+// Error - SyntaxError: Invalid or unexpected token
+// lesson learnt - variables cannot start with a number

Sprint-2a/3-mandatory-interpret/1-percentage-change.js

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+let carPrice = "10,000";
+let priceAfterOneYear = "8,543";
+
+carPrice = Number(carPrice.replaceAll(",", ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
+const priceDifference = carPrice - priceAfterOneYear;
+const percentageChange = (priceDifference / carPrice) * 100;
+
+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
+// 2
+//carPrice = Number(carPrice.replaceAll(",", ""));
+//priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ","));
+// 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?
+//b) error = SyntaxError: missing ) after argument list
+// (",", ",")); - added , between quoted values
+// c) Identify all the lines that are variable reassignment statements
+//carPrice = Number(carPrice.replaceAll(",", ""));
+//priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ","));
+// 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;
+// e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// e) cleans the amount format by removing characters such as , and leaving only number