diff --git a/js/src/common/utils/RequestError.js b/js/src/common/utils/RequestError.ts
similarity index 55%
rename from js/src/common/utils/RequestError.js
rename to js/src/common/utils/RequestError.ts
index 3346e673f..73e36f854 100644
--- a/js/src/common/utils/RequestError.js
+++ b/js/src/common/utils/RequestError.ts
@@ -1,5 +1,14 @@
 export default class RequestError {
-  constructor(status, responseText, options, xhr) {
+  status: string;
+  options: object;
+  xhr: XMLHttpRequest;
+
+  responseText: string | null;
+  response: object | null;
+
+  alert: any;
+
+  constructor(status: string, responseText: string | null, options: object, xhr: XMLHttpRequest) {
     this.status = status;
     this.responseText = responseText;
     this.options = options;