add the useInterval hook

myems-web/src/hooks/useInterval.js

@@ -0,0 +1,22 @@
+import React, { useState, useEffect, useRef } from 'react';
+
+const useInterval = (callback, delay) => {
+  const savedCallback = useRef();
+
+  // Remember the latest callback.
+  useEffect(() => {
+    savedCallback.current = callback;
+  });
+
+  // Set up the interval.
+  useEffect(() => {
+    function tick() {
+      savedCallback.current();
+    }
+    if (delay !== null) {
+      let id = setInterval(tick, delay);
+      return () => clearInterval(id);
+    }
+  }, [delay]);
+};
+export default useInterval;