Implement getOrdinalNumber

Author: Vitalii-code

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

@@ -1,5 +1,31 @@
 function getOrdinalNumber(num) {
-  return "1st";
+  // handle special cases
+
+  if (typeof num !== "number" || Number.isNaN(num)) {
+    throw new Error(`Invalid type for ${num}, expected Number`);
+  }
+
+  const snum = String(num); // num as a string
+  const thList = ["0", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13"]; // list of numbers that should end up with th as a suffix
+
+  const lastCharIndex = snum.length - 1;
+  const lastOne = snum[lastCharIndex];
+  const lastTwo = snum.slice(lastCharIndex - 1);
+
+  if (thList.includes(lastTwo) || thList.includes(lastOne)) {
+    return snum + "th";
+  }
+
+  switch (lastOne) {
+    case "1":
+      return snum + "st";
+    case "2":
+      return snum + "nd";
+    case "3":
+      return snum + "rd";
+    default:
+      break;
+  }
 }
 
 module.exports = getOrdinalNumber;