updated penceString file and expanded comments to include breakdown and rationale of the program

Author: Alex-Os-Dev-Lab

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

@@ -1,4 +1,4 @@
-const penceString = "399p";
+const penceString = "9p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
@@ -25,3 +25,98 @@ 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) : intialises a variable
+//    with the value of the penceString variable with the last character "p" removed.
+
+// a. This is achieved by using the substring method on the penceString variable
+//    the substring method enables the program to manipulate the penceSting variable by targeting and removing characters in the string.
+
+// b. The first argument of the substring method indicates the starting index; (0) which is 399p[0] = "3"
+
+// c. The second argument of the substring method indicates the ending index (penceString.length - 1)
+//    (.length) returns the length of the string object which is 4, and (-1) targets the last character in the string which is "p".
+//
+// d. Therefore, the substring method will return a new string that starts from index 0 and ends at index 3 which is "399"
+
+// e. If const penceString = "1399p" the penceStringWithoutTrailingP variable will have the value "1399"
+//    because the substring method will indicate the starting index as (0 which = "1")
+//    and the ending index as (penceString.length - 1) which is 5 - 1 = 4, which is "p"
+//    therefore it will return a new string that starts from index 0 and ends at index 4 which is "1399"
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0") : initialises a variable
+//    with the value of the penceStringWithoutTrailingP variable with padding added to the start of the string
+//    until it reaches a total length of 3 characters.
+
+// a. This is achieved by using the padStart method on the penceStringWithoutTrailingP variable
+//    the padStart method enables the program to manipulate the penceStringWithoutTrailingP variable
+//    by adding padding to the start of the string until it reaches a specified length.
+
+// b. The first argument of the padStart method indicates the target length of the resulting string which is 3 in this case.
+
+// c. The second argument of the padStart method indicates the string to use to fill or pad which is "0" in this case.
+//
+// d. Therefore, if the penceStringWithoutTrailingP variable has a length of less than 3 characters,
+//    the padStart method will add "0" characters to the start of the string until it reaches a total length of 3 characters.
+//    In this case, since penceStringWithoutTrailingP is "399" which already has a length of 3 characters,
+//    the padStart method will not add any padding and paddedPenceNumberString will also be "399".
+
+// e. if const penceStringWithoutTrailingP = "99" the paddedPenceNumberString variable will have the value "099"
+//    because the padStart method will add one "0" character to the start of the string until it reaches a total length of 3 characters.
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2) : initialises a variable
+//    with the value of the paddedPenceNumberString variable with the last two characters removed.
+
+// a. This is achieved by using the substring method on the paddedPenceNumberString variable
+//    the substring method enables the program to manipulate the paddedPenceNumberString variable by targeting and removing characters in the string.
+
+// b. The first argument of the substring method indicates the starting index; (0) which is 399[0] = "3"
+
+// c. The second argument of the substring method indicates the ending index (paddedPenceNumberString.length - 2)
+//    (.length) returns the length of the string object which is 3, and (-2) targets the last two characters in the string which is "99"
+//
+// d. Therefore it will return a new string that starts from index 0 and ends at index 1 which is "3"
+
+// d. If const paddedPenceNumberString = "099" the pounds variable will have the value "0" because the substring method
+//    will indicate the starting index as (0 which = "0") and the ending index as (paddedPenceNumberString.length - 2)
+//    which is 3 - 2 = 1, which is "9" therefore it will return a new string that starts from index 0 and ends at index 0 which is "0"
+
+// e. if penceString = "1399p" ; const penceStringWithoutTrailingP = "1399" ; const paddedPenceNumberString = "1399"
+//    because the padStart method will not add any padding since the length of penceStringWithoutTrailingP is already 4 characters
+//    which is greater than the target length of 3 characters. therefore the const pounds variable will have the value "13"
+//    because the substring method will indicate the starting index as (0 which = "1") and the ending index as
+//    (paddedPenceNumberString.length - 2) which is 4 - 2 = 2, which is "9" therefore it will return a new string that starts from index 0
+//    and ends at index 1 which is "13"
+
+// 5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0") : initialises a variable
+//    with the value of the last two characters of the paddedPenceNumberString variable with padding added to the end of the string
+//    until it reaches a total length of 2 characters.
+
+// a. This is achieved by using the substring method on the paddedPenceNumberString variable to extract the last two characters of the string,
+//    and then using the padEnd method to add padding to the end of the string until it reaches a specified length.
+
+// b. The first argument of the substring method indicates the starting index which is (paddedPenceNumberString.length - 2)
+//    which targets the last two characters in the string. The ending index is not provided, so it will extract until the end of the string.
+//
+
+// c. The padEnd method is then used on the resulting string from the substring method to add padding to the end of the string
+//    until it reaches a total length of 2 characters.
+
+// d. The first argument of the padEnd method indicates the target length of the resulting string which is 2 in this case.
+
+// e. The second argument of the padEnd method indicates the string to use to fill or pad which is "0" in this case.
+
+// f. Therefore, if the paddedPenceNumberString variable has a length of less than 2 characters, the padEnd method will add "0" characters
+//    to the end of the string until it reaches a total length of 2 characters.
+//    In this case, since paddedPenceNumberString is "399" which has a length of 3 characters,
+//    the substring method will extract the last two characters "99"
+//    and then the padEnd method will not add any padding since the length of the resulting string is already 2 characters.
+//    therefore pence will be "99"
+
+// g. if penceString = "9p" ; const penceStringWithoutTrailingP = "9" ; const paddedPenceNumberString = "009" ;
+//    const pounds = "0" ; const pence = "09" because the substring method will extract the last two characters "09"
+//    and then the padEnd method will not add any padding since the length of the resulting string is already 2 characters.
+//    therefore pence will be "09"
+
+// 6. console.log(`£${pounds}.${pence}`) : outputs the final result to the console in the format of "£pounds.pence"
+//    where pounds and pence are the values of the pounds and pence variables respectively.