work on errors,identifying codes and brief explanation of codes

Author: Abduhasen

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

@@ -1,2 +1,4 @@
-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? */
+
+/*when we try to write comment and instruction and we want the computer not to run it we can comment them using // for single line and /* for multiple lines. */

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

@@ -1,4 +1,5 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+// To reassign  a value of age we have to use let not const.

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

@@ -1,5 +1,7 @@
 // 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 code try to log the variable before declaring the variable
+// if we declare and initialize the variable first then we can use it.

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

@@ -1,4 +1,4 @@
-const cardNumber = 4533787178994213;
+const cardNumber = "4533787178994213";
 const last4Digits = cardNumber.slice(-4);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
@@ -7,3 +7,6 @@ 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 is not working because of the variable type which is .slice method work on 
+string and array variable types not on number variable types to fix it we can change the variable type to 
+string variable type by adding double quotation marks to the variable.*/

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

@@ -1,2 +1,4 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const hourClockTime12 = "20:53";
+const hourClockTime24 = "08:53";
+
+// Numbers are not allowed as the first character in naming of variables.

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

@@ -12,11 +12,26 @@ 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
+/* there are 5 function calls in this code.
+    1) Number(carPrice.replaceAll(",","")); line 4.
+    2) Number(priceAfterOneYear.replace("," "")) line 5.
+    3) carPrice.replaceAll(",", "") line 4.
+    4) priceAfterOneYear.replaceAll("," "") line 5.
+    5) console.log(`The percentage change is ${percentageChange}`);  line 10. */ 
 
 // 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?
+//the error is coming from line 5 and the error is missing between the arguments.
 
 // c) Identify all the lines that are variable reassignment statements
+/*on line 4- carPrice = Number(carPrice.replaceAll(",", ""));  
+  on line 5- priceAfterOneYear = Number(priceAfterOneYear.replaceAll(","), "")*/
 
 // d) Identify all the lines that are variable declarations
+/* line 1- let carPrice = "10,000";  
+   line 2- let priceAfterOneYear = "8,543";
+   line 7- const priceDifference = carPrice - priceAfterOneYear;
+   line 8- const percentageChange = (priceDifference / carPrice) * 100;*/
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+/* the expression doing changing the value of "10,000" to "10000" because comma count as part of a character after that 
+    changing the string variable type to number variable type. */

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

@@ -12,14 +12,23 @@ 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?
+// there are 6 variable declaration.
 
 // b) How many function calls are there?
+// there is only one 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
+/* the expression movieLength % 60 represents the returns of the remainder after dividing one number by another 
+   in this case 8784 % 60 and it return the remainder 24. */
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+//This expression calculates the total full minutes in the movie by removing leftover seconds and converting seconds to minutes.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+//result represent the total movie length using hours,minutes and seconds,the better name can be totalMovieLength.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+/*the code works for different values of movieLength it present the input movieLength by calculating the remainder and subtracting 
+it with the initial input and using the method for the finding of the value for the rest of the variables and assign the values withe 
+the variables of hours,minutes and seconds */

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

@@ -24,4 +24,26 @@ console.log(`£${pounds}.${pence}`);
 // Try and describe the purpose / rationale behind each step
 
 // To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 1. const penceString = "399p": initializes a string variable with the value "399p"
+
+/* 2. const penceStringWithoutTrailingP = penceString.substring(
+        0,
+        penceString.length - 1
+      ); : this part of the code have two steps,
+            - inside assigning of variable there is a function call that replace the string "399p" by "399"
+            - then assigning the variable penceStringWithoutTrailingP with new string "399" */
+
+/* 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0"); this initializes new string value that have
+          3 character if it's less than 3 it will add "0" in front of the string.*/
+
+/* 4.  const pounds = paddedPenceNumberString.substring(
+        0,
+        paddedPenceNumberString.length - 2
+      );  : this part of the code assigning const pound with value of string that length is 
+            reduced by -2 . */
+
+/* 5. const pence = paddedPenceNumberString
+        .substring(paddedPenceNumberString.length - 2)
+        .padEnd(2, "0"); : let's break it down this code parts it have two steps first one is .substring(paddedPenceNumberString.length - 2)
+                            Takes the last 2 characters of the string and the second is .padEnd(2, "0") Ensures the result 
+                            is at least length 2 if the length less than 2 it will add 0 at the end of the string. */