Add interpretation breakdown for 3-to-pounds.js

Author: lamlakamana-oss

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

@@ -25,3 +25,37 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// ─────────────────────────────────────────────────────────────
+// STEP-BY-STEP BREAKDOWN:
+//
+// Line 1: const penceString = "399p";
+//   Makes a variable that holds the price as text, with a "p" at the end
+//   to show it's in pence.
+//
+// Lines 3-6: const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+//   Cuts off the "p" at the end. It takes the text from the start up to
+//   (but not including) the last letter. Now we have "399".
+//
+// Line 8: const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//   Makes sure the text is at least 3 characters long. If it's shorter, it
+//   adds "0" at the front. "399" is already 3 characters, so nothing changes.
+//
+// Lines 9-12: const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+//   Takes everything except the last 2 characters. That's the pounds part.
+//   For "399", this gives us "3".
+//
+// Lines 14-16: const pence = paddedPenceNumberString
+//     .substring(paddedPenceNumberString.length - 2)
+//     .padEnd(2, "0");
+//   Takes the last 2 characters (that's the pence part). Then it makes sure
+//   there are 2 characters by adding "0" at the end if needed. For "399",
+//   this gives us "99".
+//
+// Line 18: console.log(`£${pounds}.${pence}`);
+//   Prints the final price. The result is "£3.99".
+//
+// Why do we add extra "0"s (padding)?
+//   So the price always looks right. Without it, a price like "5p" would
+//   show up as "£0.5" (wrong) instead of "£0.05" (right).
+// ─────────────────────────────────────────────────────────────