diff --git a/BinarySearch/IndexOf_BinarySearch.test.ts b/BinarySearch/IndexOf_BinarySearch.test.ts
new file mode 100644
index 0000000..e69de29
diff --git a/BinarySearch/IndexOf_BinarySearch.ts b/BinarySearch/IndexOf_BinarySearch.ts
new file mode 100644
index 0000000..4336388
--- /dev/null
+++ b/BinarySearch/IndexOf_BinarySearch.ts
@@ -0,0 +1,34 @@
+const indexOf_BinarySearch = (dataArr: number[], num: number): number => {
+  let n1 = 0;
+  let n2 = dataArr.length - 1;
+
+  if (n1 === num) return n1;
+  if (n2 === num) return n2;
+
+  while (n1 <= n2) {
+    const mid = Math.floor((n1 + n2) / 2);
+
+    if (num > dataArr[mid]) {
+      n1 = mid + 1;
+    } else if (num < dataArr[mid]) {
+      n2 = mid - 1;
+    } else {
+      return mid;
+    }
+  }
+
+  return -1;
+};
+
+// const arr = [];
+// for (let index = 0; index < 100000000; index++) {
+//   arr.push(index);
+// }
+
+// console.time("indexOf_BinarySearch");
+// indexOf_BinarySearch(arr, 99999999)
+// console.timeEnd("indexOf_BinarySearch");
+
+// console.time("indexOf");
+// arr.indexOf(99999999)
+// console.timeEnd("indexOf");