diff --git a/src/libs/hashCode.js b/src/libs/hashCode.ts
similarity index 80%
rename from src/libs/hashCode.js
rename to src/libs/hashCode.ts
index a95d0787a6e3..bb0522c25de0 100644
--- a/src/libs/hashCode.js
+++ b/src/libs/hashCode.ts
@@ -2,11 +2,11 @@
 /**
  * Simple string hashing function obtained from: https://stackoverflow.com/a/8831937/16434681
  * Returns a hash code from a string
- * @param  {String} str The string to hash.
- * @return {Number} A 32bit integer (can be negative)
+ * @param str The string to hash.
+ * @return A 32bit integer (can be negative)
  * @see http://werxltd.com/wp/2010/05/13/javascript-implementation-of-javas-string-hashcode-method/
  */
-function hashCode(str) {
+function hashCode(str: string): number {
     let hash = 0;
     for (let i = 0, len = str.length; i < len; i++) {
         const chr = str.charCodeAt(i);