Cape Town | 26-ITP-SEP | Liyema Mfengwana | Sprint 2 | Course-work-2

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

@@ -4,3 +4,4 @@ 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
+// line 3 increments count by 1 and reassigns updated value back to the count variable

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

@@ -1,10 +1,15 @@
-const firstName = "Creola";
-const middleName = "Katherine";
-const lastName = "Johnson";
+let firstName = "Creola";
+let middleName = "Katherine";
+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.
 
-const initials = ``;
+let firstName = "Chris";
+let middleName = "Kevin";
+let lastName = "Jones";
 
+let initials = `${firstName[0]}${middleName[0]}${lastName[0]}`;
+
+console.log(initials);
 // https://www.google.com/search?q=get+first+character+of+string+mdn

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

@@ -17,7 +17,31 @@ 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 filePath = "Documents/work/report.pdf";
 
-// https://www.google.com/search?q=slice+mdn
+const lastSlashIndex = filePath.lastIndexOf("/");
+const lastDotIndex = filePath.lastIndexOf(".");
+
+const dir = filePath.slice(0, lastSlashIndex);
+const ext = lastDotIndex === -1 ? "" : filePath.slice(lastDotIndex);
+
+console.log(dir);
+console.log(ext);
+
+const lastSlashIndex = filePath.lastIndexOf("/");
+const lastDotIndex = filePath.lastIndexOf(".");
+
+// Store the directory
+const dir = filePath.slice(0, lastSlashIndex);
+
+// Store the extension
+const ext = lastDotIndex === -1 ? "" : filePath.slice(lastDotIndex);
+
+console.log(dir);
+console.log(ext);
+lastDotIndex;
+
+console.log(`The dir part of ${filePath} is ${dir}`);
+console.log(`The ext part of ${filePath} is ${ext}`);
+
+// https://www.google.com/search?q=slice+mdn

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

@@ -7,3 +7,13 @@ 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
+
+// Print the random number to the console
+console.log(num);
+
+//num is a random whole number between 1 and 100.
+
+//Math.random() creates a random decimal.
+//Multiply by the range size.
+// Math.floor() rounds down.
+// Add minimum so it starts at 1.

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

@@ -1,4 +1,4 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;

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

@@ -1,5 +1,5 @@
 // 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}`);

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

@@ -1,9 +1,16 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().slice(-4);
 
 // 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
+
+//I predict the code will not work because cardNumber is a number and .slice() is used on strings (or arrays), not numbers.
+//When you run it, JavaScript gives an error which is TypeError: cardNumber.slice is not a function
+//the reason is because creates a number, and numbers do not have a .slice() method.
+//the fix is converting the number to a string
+
+console.log(last4Digits);

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

@@ -1,2 +1,4 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";
+
+//the code will fail because variable names cannot start with a number

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

@@ -20,3 +20,33 @@ 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?
+
+//answers
+
+/* a) there are there five
+     carPrice.replaceAll(",", "")
+     Number(carPrice.replaceAll(",", ""))
+     Number(priceAfterOneYear.replaceAll(",", ""))
+     console.log(...) -
+     (priceDifference / carPrice) * 100 - line 7 (this is an expression that involves division and multiplication, but it does not involve a function call)*/
+
+
+/* b) priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", "")); 
+The issue is  a syntax mistake in the brackets/quotes, and JavaScript throws a SyntaxError before running.
+
+the fix would be priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
+*/
+
+/* c)carPrice = Number(carPrice.replaceAll(",", ""));
+     priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));*/
+
+/* d) let carPrice = "10,000";
+let priceAfterOneYear = "8,543";
+const priceDifference = carPrice - priceAfterOneYear;
+const percentageChange = (priceDifference / carPrice) * 100;*/
+
+/* e)carPrice is a string:
+    replaceAll(",", "") removes commas:
+    Number(...) converts string to a number:
+    Convert a formatted string number into a real numeric value so calculations can work.*/

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

@@ -13,13 +13,34 @@ console.log(result);
 
 // a) How many variable declarations are there in this program?
 
+/* there are 6 variable declarations
+const movieLength = 8784;
+const remainingSeconds = movieLength % 60;
+const totalMinutes = (movieLength - remainingSeconds) / 60;
+const remainingMinutes = totalMinutes % 60;
+const totalHours = (totalMinutes - remainingMinutes) / 60;
+const result = `${totalHours}:${remainingMinutes}:${remainingSeconds}`;*/
+
 // b) How many function calls are there?
 
+/* there is one function call 
+   console.log(result);*/
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+//The % operator is called the modulus (remainder) operator.
+//it means Divide movieLength by 60 and return the remainder
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+//This means:Convert the total seconds into full minutes without the leftover seconds
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+//A time format (hours:minutes:seconds) for the movie length, a better name would be movieDuration
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+//No, it will not work perfectly for all values.
+//It does not add leading zeros (so you get 2:5:7 instead of 02:05:07)
+//The format can look wrong for some numbers

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

@@ -1,20 +1,31 @@
+//Creates a string that represents a price in pence (with a “p” at the end).
 const penceString = "399p";
 
+/*Removes the last character "p"
+So "399p" becomes "399".*/
 const penceStringWithoutTrailingP = penceString.substring(
   0,
   penceString.length - 1
 );
 
+//Makes sure the number has at least 3 digits.
+//If it's shorter, it adds leading zeros.
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+//Takes everything except the last 2 digits.
+//This becomes the pounds part.
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
 
+//Takes the last 2 digits as pence.
+//If needed, it adds a trailing zero to make sure it always has 2 digits.
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
 
+//Prints the final formatted price in pounds and pence format.
 console.log(`£${pounds}.${pence}`);
 
 // This program takes a string representing a price in pence

Sprint-2/4-stretch-explore/chrome.md

@@ -1,11 +1,14 @@
-Open a new window in Chrome, right click an empty space on the page, select **Inspect** from the dropdown, then locate the **Console** tab.
+Open a new window in Chrome,
+
+then locate the **Console** tab.
 
 Voila! You now have access to the [Chrome V8 Engine](https://www.cloudflare.com/en-gb/learning/serverless/glossary/what-is-chrome-v8/).
 Just like the Node REPL, you can input JavaScript code into the Console tab and the V8 engine will execute it.
 
 Let's try an example.
 
-In the Chrome console, invoke the function `alert` with one argument, the string `"Hello world!"`;
+In the Chrome console,
+invoke the function `alert` with an input string of `"Hello world!"`;
 
 What effect does calling the `alert` function have?