detailed explanation about the code

Author: AkliluMihtsun

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

@@ -2,13 +2,13 @@ const penceString = "399p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
-  penceString.length - 1
+  penceString.length - 1,
 );
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
 const pounds = paddedPenceNumberString.substring(
   0,
-  paddedPenceNumberString.length - 2
+  paddedPenceNumberString.length - 2,
 );
 
 const pence = paddedPenceNumberString
@@ -25,3 +25,43 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// 2. From line 3 to line 6 const penceStringWithoutTrailingP is declared and it will hold the value of
+// penceString.substring(0, penceString.length - 1)
+// which is "399". We got this value by the method substring(0, penceString.length - 1) called by penceString
+// Breaking down the expression penceString.substring(0, penceString.length - 1)
+// a) penceString.length - 1 this counts the number of characters in the penceString String and then subtracts 1 from it (4-1=3)
+// then it will look like this penceString.substring(0, 3)
+// b) penceString.substring(0, penceString.length - 1) then the substring method called by penceString
+// is used produce a slice of small string from a big string
+// it takes two arguments the first one tells where to start slicing and the second one tells where to stop
+// (but the last character is not included)
+// Therefore const penceStringWithoutTrailingP will be assigned "399"
+
+// 3. In line 8 const paddedPenceNumberString is declared and it will hold the value of penceStringWithoutTrailingP.padStart(3, "0")
+// which is still "399". In this expression we used the method padStart called by penceStringWithoutTrailingP and this method is basically
+// adds characters at the start of our String. It takes two arguments the first one is telling how many characters we want in our String
+// and second argument tells the character that needs to be added so that we get out desired number of characters in our String.
+// since our String length is 3 the method will not do anything
+
+// 4. From line 9 to line 12 const pounds is declared and it will hold the value of paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2,)
+// which is "3". We got this value by the method substring(0, paddedPenceNumberString.length - 2,) called by paddedPenceNumberString
+// Breaking down the expression paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2,)
+// a) paddedPenceNumberString.length - 2 this counts the number of characters in the paddedPenceNumberString then subtracts 2 from it (3-2=1)
+// then it will look like this paddedPenceNumberString.substring(0, 1)
+// b) paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2,) then the substring method called by paddedPenceNumberString is used to
+// produce a slice of small string from a big string
+// it takes two arguments the first one tells where to start slicing and the second one tells where to stop
+// (but the last character is not included)
+// Therefore const pounds will assigned "3"
+
+// 5. From line 14 to line 16 const pence is declared and it will hold the value of
+// paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0") which is "99"
+// Breaking down the expression
+// a) paddedPenceNumberString.length - 2 this will count the number of characters in paddedPenceNumberString and then subtracts 2 from it (3-2=1)
+// paddedPenceNumberString.substring(paddedPenceNumberString.length - 2) then this substring method will produce small string from it starting from index 1 which will be "99"
+//then finally paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0") the padEnd method will add characters at the end of the String
+// and  will take two arguments first will tell how many characters we need in our string and the second will tell the character that needs to be added
+// since our String length is 2 the method will do nothing
+
+// 6. Finally line 18 will print out the desired format we have added what to be printed inside the back-ticks if they are variables we will put them in ${}