@@ -0,0 +1,46 @@
+//@ts-check
+/**
+ *@author  Damola Adekoya
+ * @param {Array} arr
+ */
+
+const mergeSort = arr => {
+  if (arr.length <= 1) return arr; //determine the end condition for recursive loop
+  let mid = Math.floor(arr.length / 2);
+  let left = mergeSort(arr.slice(0, mid));
+  let right = mergeSort(arr.slice(mid, arr.length));
+  return merge(left, right);
+};
+
+/**
+ *
+ * @param {Array} arr1
+ * @param {Array} arr2
+ */
+
+const merge = (arr1, arr2) => {
+  let result = []; //hold the new merge array
+  let i = 0;
+  let j = 0; //keep track of the current position in the loop
+  while (i < arr1.length && j < arr2.length) {
+    if (arr2[j] > arr1[i]) {
+      result.push(arr1[i]);
+      i++;
+    } else {
+      result.push[arr2[j]];
+      j++;
+    }
+  }
+
+  // Push the leftover Array Element if arr1 and arr2 length not equal
+  while (i < arr1.length) {
+    result.push(arr1[i]);
+    i++;
+  }
+  while (j < arr2.length) {
+    result.push(arr2[j]);
+    j++;
+  }
+
+  return result;
+};