London | 26-ITP-May | Khaliun Baatarkhuu | Sprint 1 | Coursework

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

@@ -2,5 +2,9 @@ let count = 0;
 
 count = count + 1;
 
+// The assignment operator (=) stores the result of count + 1 in the variable count. i.e. incrementing the count by 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
+
+

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

@@ -1,11 +1,16 @@
+// 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 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.
+let initials = firstName[0] + middleName[0] + lastName[0];
+
+console.log(initials);
+
+//I have run this code on chrome console and the answer was CKJ
+
 
-let initials = ``;
 
-// https://www.google.com/search?q=get+first+character+of+string+mdn
 

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

@@ -15,9 +15,10 @@ const base = filePath.slice(lastSlashIndex + 1);
 console.log(`The base part of ${filePath} is ${base}`);
 
 // Create a variable to store the dir part of the filePath variable
+const dir = filePath.slice(0, lastSlashIndex);
+
 // Create a variable to store the ext part of the variable
 
-const dir = ;
-const ext = ;
+const ext = base.slice(base.lastIndexOf(".") + 1);
 
-// https://www.google.com/search?q=slice+mdn
+// https://www.google.com/search?q=slice+mdn

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

@@ -3,7 +3,22 @@ const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 
+
 // 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
+
+//Expressions in JS are evaluated from inside out, following the brackets. So (maximum - minimum + 1) would become 100-1+1=100.
+//Then we move on to the next outer bracket "Math.random()", which is a function designed to generate random numbers. We multiply that random number
+//by 100 and that is our brackets calculated for now. Next in the expression is the function "math.floor" which rounds down numbers to the 
+//nearest whole number, to which we add the minimum at the end. Which is number 1. 
+
+// I have run this code on my Chrome console multiple times and got a diffrent number each time. 
+
+const minimum = 1;
+const maximum = 100;
+
+const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+
+console.log(num);

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

@@ -1,2 +1,10 @@
 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?
+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?
+
+/*
+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

@@ -2,3 +2,14 @@
 
 const age = 33;
 age = age + 1;
+
+/*
+Error here is that value for "const" cannot be reassigned. If we wanna see the code work 
+we must use "let" keyword because the variable can be changed. 
+*/
+
+let age = 33;
+age = age + 1;
+console.log(age);
+
+//I have ran this code and got 34 on chrome console 

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

@@ -3,3 +3,8 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+//We must declare the variable first then use it, because JS reads from top to bottom.
+
+const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);

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

@@ -7,3 +7,19 @@ const last4Digits = cardNumber.slice(-4);
 // 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
+
+
+
+/*
+The code won't work because the cardNumber is a numeric value and "slice()" works with strings in JS.
+I have run the code to get "VM1691:2 Uncaught TypeError: cardNumber.slice is not a function" error.
+I guess, JS is trying to find slice function on the cardNumber and since it is not a string it confirms 
+that it is in fact not a function.
+*/
+
+const cardNumber = 4533787178994213;
+const last4Digits = cardNumber.toString().slice(-4);
+
+console.log(last4Digits);
+
+//this code worked because i have converted the cardNumber value to string then sliced the last four digits.

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

@@ -1,2 +1,9 @@
 const 12HourClockTime = "8:53pm";
 const 24hourClockTime = "20:53";
+
+/* 
+I have predicted the code won't run due to the fact that "8:53pm" should be "08:53"
+Got this error "Uncaught SyntaxError: Invalid or unexpected token", meaning it is a syntax error. 
+I have searched it up to find that variables can't start with numbers because it makes it easier 
+for JS to read code by removing a mathematical ambiguity.
+*/

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

@@ -13,10 +13,31 @@ console.log(`The percentage change is ${percentageChange}`);
 
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
 
+/*
+There are three function call names, but two functions have been made twice inside another, adding up to five function calls being made overall. 
+1. carPrice.replaceAll(",", "")
+2. Number(carPrice.replaceAll(",", ""))  this expression contain two, one inside the other
+3. priceAfterOneYear.replaceAll(",", "")
+4. Number(priceAfterOneYear.replaceAll(",", "")) this expression contains two as well 
+5. console.log(`The percentage change is ${percentageChange}`)
+*/
+
 // 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?
 
+//I have run the code and got a syntax error on line 5, due to two arguments not being seperated by a comma.
+
 // 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?
+
+//Removing all the comma for calculation then convert the string into a number.

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

@@ -13,13 +13,26 @@ console.log(result);
 
 // a) How many variable declarations are there in this program?
 
+// Six, every line that starts with "const" keyword.
+
 // b) How many function calls are there?
 
+// One, line 10.
+
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
 
+// It calculates how many seconds are left over.
+
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
 
+// It first removes the leftover seconds from the total movie length, then converts the remaining seconds into minutes.
+
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
+// It represents a formatted time string and since it's a movie, i would change "result" variable to "movieDuration".
+
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// The code wouldn't work with decimal numbers "because movieLength" is a whole number, also negative numbers won't work
+//because movies can't be less than zero.

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

@@ -1,22 +1,35 @@
-const penceString = "399p";
+const penceString = "399p"; // This line shows price in pence with a letter "p" attached at the end.
 
-const penceStringWithoutTrailingP = penceString.substring(
-  0,
-  penceString.length - 1
-);
+
+const penceStringWithoutTrailingP = penceString.substring(0,penceString.length - 1);
+
+// Above line of code removes the "p", using "penceString.substring" function by removing the last character with "-1",
+//out of a four digit string "399p".
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
-const pounds = paddedPenceNumberString.substring(
-  0,
-  paddedPenceNumberString.length - 2
-);
 
-const pence = paddedPenceNumberString
-  .substring(paddedPenceNumberString.length - 2)
+// We are using "padstart" method to ensure the string contains three characters at least, 
+//and if necessary to add "0" to the front.
+
+
+const pounds = paddedPenceNumberString.substring(0,paddedPenceNumberString.length - 2);
+
+// We are calculating the pounds const variable by taking away the last two digits from "paddedPenceNumberString" const.
+
+const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2)
   .padEnd(2, "0");
 
+//First we extracting the last two digits with "(paddedPenceNumberString.length - 2)", then making ensure the pence part
+//has two digits always with "padEnd(2, "0")". Basically calculating the const pence variable. 
+
 console.log(`£${pounds}.${pence}`);
 
+//Uses a template literal to combine the pounds and pence values into a currency format and prints the result to the console.
+
+
+
+
+
 // This program takes a string representing a price in pence
 // The program then builds up a string representing the price in pounds