Add hook for API polling.

src/api/hooks.js

@@ -5,7 +5,9 @@
  * See /LICENSE for more information.
  */
 
-import { useCallback, useReducer } from "react";
+import {
+    useCallback, useEffect, useReducer, useState,
+} from "react";
 
 import { ForisURLs } from "forisUrls";
 import {
@@ -90,3 +92,23 @@ const useAPIDelete = createAPIHook("DELETE");
 export {
     useAPIGet, useAPIPost, useAPIPatch, useAPIPut, useAPIDelete,
 };
+
+export function useAPIPolling(endpoint, delay) {
+    const [state, setState] = useState({ state: API_STATE.INIT });
+    const [getState, get] = useAPIGet(endpoint);
+
+    useEffect(() => {
+        if (getState.state === API_STATE.SUCCESS) {
+            setState(getState);
+        }
+    }, [getState]);
+
+    useEffect(() => {
+        if (delay !== null) {
+            const interval = setInterval(get, delay);
+            return () => clearInterval(interval);
+        }
+    }, [delay, get]);
+
+    return [state];
+}

src/index.js

@@ -7,7 +7,12 @@
 
 // API
 export {
-    useAPIGet, useAPIPost, useAPIPatch, useAPIPut, useAPIDelete,
+    useAPIGet,
+    useAPIPost,
+    useAPIPatch,
+    useAPIPut,
+    useAPIDelete,
+    useAPIPolling,
 } from "api/hooks";
 export { API_STATE } from "api/utils";