Refactor countChar function to return early for invalid inputs and remove redundant code

Author: Iswanna

Sprint-3/2-practice-tdd/count.js

@@ -1,21 +1,23 @@
 function countChar(stringOfCharacters, findCharacter) {
-  let characterOccurrence = "";
+  // Check both inputs are strings
   if (
-    typeof stringOfCharacters === "string" &&
-    typeof findCharacter === "string"
+    typeof stringOfCharacters !== "string" ||
+    typeof findCharacter !== "string"
   ) {
-    stringOfCharacters = stringOfCharacters.toLowerCase();
-    findCharacter = findCharacter.toLowerCase();
-    if (findCharacter.length === 1) {
-      characterOccurrence = stringOfCharacters.split(findCharacter).length - 1;
-    } else {
-      characterOccurrence = "invalid input: Input just one character";
-    }
-  } else {
-    characterOccurrence = "Invalid input: input should be a string";
+    return "Invalid input: input should be a string";
   }
 
-  return characterOccurrence;
+  // Convert both to lowercase for case-insensitive matching
+  const str = stringOfCharacters.toLowerCase();
+  const char = findCharacter.toLowerCase();
+
+  // Check that only one character is passed
+  if (char.length !== 1) {
+    return "invalid input: Input just one character";
+  }
+
+  // Return count (0 for empty strings works naturally)
+  return str.split(char).length - 1;
 }
 
 module.exports = countChar;