Lazy load components (#3879)

* feat: Lazy-load routes

* feat: Lazy-load modals

* feat: Lazy-load columns

* refactor: Simplify Bundle API

* feat: Optimize bundles

* feat: Prevent flashing the waiting state

* feat: Preload commonly used bundles

* feat: Lazy load Compose reducers

* feat: Lazy load Notifications reducer

* refactor: Move all dynamic imports into one file

* fix: Minor bugs

* fix: Manually hydrate the lazy-loaded reducers

* refactor: Move all dynamic imports to async-components

* fix: Loading modal style

* refactor: Avoid converting the raw state for each lazy hydration

* refactor: Remove unused component

* refactor: Maintain modal name

* fix: Add as=script to preload link

* chore: Fix lint error

* fix(components/bundle): Check if timestamp is set when computing elapsed

* fix: Load compose reducers for the onboarding modal

1 files changed, 13 insertions, 0 deletions

diff --git a/app/javascript/mastodon/features/ui/components/column_loading.js b/app/javascript/mastodon/features/ui/components/column_loading.js
new file mode 100644
index 000000000..9bb9c14a1
--- /dev/null
+++ b/app/javascript/mastodon/features/ui/components/column_loading.js
@@ -0,0 +1,13 @@
+import React from 'react';
+
+import Column from '../../../components/column';
+import ColumnHeader from '../../../components/column_header';
+
+const ColumnLoading = () => (
+  <Column>
+    <ColumnHeader icon=' ' title='' multiColumn={false} />
+    <div className='scrollable' />
+  </Column>
+);
+
+export default ColumnLoading;