Refactor getOrdinalNumber function to return early for invalid input and remove redundant code

Author: Iswanna

Sprint-3/2-practice-tdd/get-ordinal-number.js

@@ -1,31 +1,25 @@
 function getOrdinalNumber(num) {
-  let ordinalNum;
-  if (Number.isInteger(num) === true) {
-    if (
-      Math.abs(num % 100) === 11 ||
-      Math.abs(num % 100) === 12 ||
-      Math.abs(num % 100) === 13 ||
-      Math.abs(num % 10) === 4 ||
-      Math.abs(num % 10) === 5 ||
-      Math.abs(num % 10) === 6 ||
-      Math.abs(num % 10) === 7 ||
-      Math.abs(num % 10) === 8 ||
-      Math.abs(num % 10) === 9 ||
-      Math.abs(num % 10) === 0
-    ) {
-      ordinalNum = `${num}th`;
-    } else if (Math.abs(num % 10) === 1) {
-      ordinalNum = `${num}st`;
-    } else if (Math.abs(num % 10) === 2) {
-      ordinalNum = `${num}nd`;
-    } else if (Math.abs(num % 10) === 3) {
-      ordinalNum = `${num}rd`;
-    } else {
-      ordinalNum = `${num}th`;
-    }
-  } else {
-    ordinalNum = "Invalid input: Input is an integer";
+  // Early return for invalid inputs
+  if (!Number.isInteger(num)) {
+    return "Invalid input: Input is an integer";
   }
-  return ordinalNum;
+
+  const absNum = Math.abs(num);
+  const lastTwo = absNum % 100;
+  const lastDigit = absNum % 10;
+
+  // Handle special cases: 11th, 12th, 13th
+  if (lastTwo === 11 || lastTwo === 12 || lastTwo === 13) {
+    return `${num}th`;
+  }
+
+  // Handle regular suffixes
+  if (lastDigit === 1) return `${num}st`;
+  if (lastDigit === 2) return `${num}nd`;
+  if (lastDigit === 3) return `${num}rd`;
+
+  // Default suffix
+  return `${num}th`;
 }
+
 module.exports = getOrdinalNumber;