diff --git a/javascript/1524-number-of-sub-arrays-with-odd-sum.js b/javascript/1524-number-of-sub-arrays-with-odd-sum.js
new file mode 100644
index 000000000..dfbd4171b
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+++ b/javascript/1524-number-of-sub-arrays-with-odd-sum.js
@@ -0,0 +1,33 @@
+/**
+ * Sliding Window | Counting
+ * Time O(n) | Space O(1)
+ * https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum
+ * @param {number[]} arr
+ * @return {number}
+ */
+var numOfSubarrays = function(arr) {
+    
+    let odds = 0;
+    let evens = 0;
+    let total = 0;
+    let currTotal = 0;
+    const mod = 10**9 + 7;
+
+    for (const num of arr) {
+        currTotal += num;
+
+        // if odd
+        if (currTotal%2) {
+            odds++;
+            total = (total + 1 + evens) % mod;
+        }
+
+        // if even
+        if (!(currTotal%2)) {
+            evens++;
+            total = (total + odds) % mod;
+        }
+    }
+
+    return total%mod;
+};