Implement tally function to count occurrences of elements in an array with input validation

Author: alexandru-pocovnicu

Sprint-2/implement/tally.js

@@ -1,3 +1,17 @@
-function tally() {}
+function tally(arr) {
+const objectCount={}
+if(!Array.isArray(arr)){
+    throw new Error("Invalid input");
+}
+if(arr.length===0){
+    return {}
+}
+for(const element of arr){
+    objectCount[element]=objectCount[element] ? objectCount[element] +1:1;
+}
+return objectCount
+
+}
+
 
 module.exports = tally;