breakdown of code explained

Author: zilinskyte

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

@@ -1,21 +1,42 @@
 const penceString = "399p";
+// Declares constant variable named penceString and assigns the string 399p
+// This indicates price in pence
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
   penceString.length - 1
 );
+// Constant variable is declared to remove the trailing p in 399p to just keep the numeric part
+// penceString.length is number of characters in 399p = 4 so -1 is 3
+// substring(0, 3) returns the characters from index 0 up to index 3 exclusive, returning 399.
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// padStart ensures that the string has at least 3 characters by adding leading zeros if necessary
+// This standardises the numeric string to simplify splitting into pounds and pence.
+// In this case, 399 already has 3 characters, so no padding is added.
+
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
+// The last two characters represent pence
+// Const pounds is declared as a variable consisting of a substring of previously declared variable and a newly calculated variable
+// paddedPenceNumberString.length computes index where last two characters start, so that is after 1 character.
+// substring(0, 1) extracts the pounds part, by returning the characters from index 0 up to index 1 exclusive. 
+// This is "3" in this case.
 
-const pence = paddedPenceNumberString
-  .substring(paddedPenceNumberString.length - 2)
-  .padEnd(2, "0");
+const pence = paddedPenceNumberString 
+// New variable to ensure two-digit pence component is formatted correctly.
+  .substring(paddedPenceNumberString.length - 2) 
+  // returns substring from index to the end inclusive
+  // For 399, start index is character 1 (the first 9) so this returns 99.
+  .padEnd(2, "0"); 
+  // Ensures pence string has at least 2 characters by adding trailing zeros if needed
+  // So 5p would become 005 and this would return 05.
 
 console.log(`£${pounds}.${pence}`);
+// Template string  that joins pounds and pence parts with a decimal point and logs it
+// This displays the standard and prints it 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