Restore vanilla components

app/javascript/mastodon/reducers/alerts.js

@@ -0,0 +1,25 @@
+import {
+  ALERT_SHOW,
+  ALERT_DISMISS,
+  ALERT_CLEAR,
+} from '../actions/alerts';
+import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
+
+const initialState = ImmutableList([]);
+
+export default function alerts(state = initialState, action) {
+  switch(action.type) {
+  case ALERT_SHOW:
+    return state.push(ImmutableMap({
+      key: state.size > 0 ? state.last().get('key') + 1 : 0,
+      title: action.title,
+      message: action.message,
+    }));
+  case ALERT_DISMISS:
+    return state.filterNot(item => item.get('key') === action.alert.key);
+  case ALERT_CLEAR:
+    return state.clear();
+  default:
+    return state;
+  }
+};