Implemented toPounds() function to convert pence strings into pounds.pence format

Author: Eugenie-A

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

@@ -4,3 +4,26 @@
 // You will need to declare a function called toPounds with an appropriately named parameter.
 
 // You should call this function a number of times to check it works for different inputs
+
+// Converts a string representing pence (e.g. "399") 
+// into pounds.pence format (e.g. "3.99")
+// MDN References used:
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring
+
+// Converts a pence string (e.g. "399")
+function toPounds(penceString) {
+  // Ensure the string is atleast 3 characters long by padding with leading zeros if needed
+  // e.g. "5" → "005", "99" → "099", "399" stays "399"
+  const padded = penceString.padStart(3, "0");
+  // Extract everything except the last two digits → this becomes the pounds
+  // e.g. "399" → "3"
+  const pounds = padded.substring(0, padded.length - 2);
+  // Extract the last two digits → this becomes the pence 
+  // e.g. "399" → "99"
+  const pence = padded.substring(padded.length - 2);
+  // Combines pounds and pence into the final money format
+  return `${pounds}.${pence}`;
+}
+
+console.log(toPounds("399")); // 3.99