feat(v2): 🔥 🔥 better loading UX ⚡️ (#1383)

* feat(v2): render old screen while loading

* replace and remove stuff

* spacing

* add spinner back, just as a fallback

* nits

* Turn off loading spinner on top right

* address review

packages/docusaurus/lib/client/App.js

@@ -7,13 +7,13 @@
 
 import React, {useState} from 'react';
 import {renderRoutes} from 'react-router-config';
-import ReactListenerProvider from 'react-listener-provider';
 
 import Head from '@docusaurus/Head'; // eslint-disable-line
 import routes from '@generated/routes'; // eslint-disable-line
 import metadata from '@generated/metadata'; // eslint-disable-line
 import siteConfig from '@generated/docusaurus.config'; //eslint-disable-line
 import DocusaurusContext from '@docusaurus/context'; // eslint-disable-line
+import PendingNavigation from './PendingNavigation';
 
 function App() {
   const [context, setContext] = useState({});
@@ -36,7 +36,9 @@ function App() {
           type="text/css"
         />
       </Head>
-      <ReactListenerProvider>{renderRoutes(routes)}</ReactListenerProvider>
+      <PendingNavigation routes={routes}>
+        {renderRoutes(routes)}
+      </PendingNavigation>
     </DocusaurusContext.Provider>
   );
 }

packages/docusaurus/lib/client/PendingNavigation.js

@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import React from 'react';
+import {Route, withRouter} from 'react-router-dom';
+import nprogress from 'nprogress';
+import 'nprogress/nprogress.css';
+import preload from './preload';
+
+nprogress.configure({showSpinner: false});
+
+class PendingNavigation extends React.Component {
+  constructor(props) {
+    super(props);
+
+    this.progressBarTimeout = null;
+    this.state = {
+      previousLocation: null,
+    };
+  }
+
+  componentWillReceiveProps(nextProps) {
+    const navigated = nextProps.location !== this.props.location;
+    const {routes, delay = 1000} = this.props;
+
+    if (navigated) {
+      window.scrollTo(0, 0);
+
+      this.startProgressBar(delay);
+      // save the location so we can render the old screen
+      this.setState({
+        previousLocation: this.props.location,
+      });
+
+      // load data while the old screen remains
+      preload(routes, nextProps.location.pathname)
+        .then(() => {
+          this.setState(
+            {
+              previousLocation: null,
+            },
+            this.stopProgressBar,
+          );
+        })
+        .catch(e => console.warn(e));
+    }
+  }
+
+  clearProgressBarTimeout() {
+    if (this.progressBarTimeout) {
+      clearTimeout(this.progressBarTimeout);
+      this.progressBarTimeout = null;
+    }
+  }
+
+  startProgressBar(delay) {
+    this.clearProgressBarTimeout();
+    this.progressBarTimeout = setTimeout(() => {
+      nprogress.start();
+    }, delay);
+  }
+
+  stopProgressBar() {
+    this.clearProgressBarTimeout();
+    nprogress.done();
+  }
+
+  render() {
+    const {children, location} = this.props;
+    const {previousLocation} = this.state;
+
+    // use a controlled <Route> to trick all descendants into
+    // rendering the old location
+    return (
+      <Route location={previousLocation || location} render={() => children} />
+    );
+  }
+}
+
+export default withRouter(PendingNavigation);

packages/docusaurus/lib/client/exports/Link.js

@@ -6,15 +6,15 @@
  */
 
 import React, {useEffect} from 'react';
-import Perimeter from 'react-perimeter';
 import {NavLink} from 'react-router-dom';
 
 const internalRegex = /^\/(?!\/)/;
 
 function Link(props) {
-  const {to, href, preloadProximity = 20} = props;
+  const {to, href} = props;
   const targetLink = to || href;
   const isInternal = internalRegex.test(targetLink);
+  let preloaded = false;
 
   const IOSupported =
     typeof window !== 'undefined' && 'IntersectionObserver' in window;
@@ -47,6 +47,13 @@ function Link(props) {
     }
   };
 
+  const onMouseEnter = () => {
+    if (!preloaded) {
+      window.docusaurus.preload(targetLink);
+      preloaded = true;
+    }
+  };
+
   useEffect(() => {
     // If IO is not supported. We prefetch by default (only once)
     if (!IOSupported && isInternal) {
@@ -64,12 +71,12 @@ function Link(props) {
     // eslint-disable-next-line jsx-a11y/anchor-has-content
     <a {...props} href={targetLink} />
   ) : (
-    <Perimeter
-      padding={preloadProximity}
-      onBreach={() => window.docusaurus.preload(targetLink)}
-      once>
-      <NavLink {...props} innerRef={handleRef} to={targetLink} />
-    </Perimeter>
+    <NavLink
+      {...props}
+      onMouseEnter={onMouseEnter}
+      innerRef={handleRef}
+      to={targetLink}
+    />
   );
 }
 

packages/docusaurus/package.json

@@ -55,13 +55,12 @@
     "is-wsl": "^1.1.0",
     "lodash": "^4.17.11",
     "mini-css-extract-plugin": "^0.4.1",
+    "nprogress": "^0.2.0",
     "portfinder": "^1.0.13",
     "react-dev-utils": "^8.0.0",
     "react-helmet": "^6.0.0-beta",
-    "react-listener-provider": "^0.2.0",
     "react-loadable": "^5.5.0",
     "react-loadable-ssr-addon": "^0.1.6",
-    "react-perimeter": "^0.4.0",
     "react-router-config": "^5.0.0",
     "react-router-dom": "^5.0.0",
     "semver": "^6.0.0",

yarn.lock

@@ -9509,6 +9509,11 @@ npm-which@^3.0.1:
     gauge "~2.7.3"
     set-blocking "~2.0.0"
 
+nprogress@^0.2.0:
+  version "0.2.0"
+  resolved "https://registry.yarnpkg.com/nprogress/-/nprogress-0.2.0.tgz#cb8f34c53213d895723fcbab907e9422adbcafb1"
+  integrity sha1-y480xTIT2JVyP8urkH6UIq28r7E=
+
 nth-check@^1.0.2, nth-check@~1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/nth-check/-/nth-check-1.0.2.tgz#b2bd295c37e3dd58a3bf0700376663ba4d9cf05c"
@@ -10986,11 +10991,6 @@ react-is@^16.8.1, react-is@^16.8.4:
   resolved "https://registry.yarnpkg.com/react-is/-/react-is-16.8.5.tgz#c54ac229dd66b5afe0de5acbe47647c3da692ff8"
   integrity sha512-sudt2uq5P/2TznPV4Wtdi+Lnq3yaYW8LfvPKLM9BKD8jJNBkxMVyB0C9/GmVhLw7Jbdmndk/73n7XQGeN9A3QQ==
 
-react-listener-provider@^0.2.0:
-  version "0.2.0"
-  resolved "https://registry.yarnpkg.com/react-listener-provider/-/react-listener-provider-0.2.0.tgz#fb6ce123f9e20ad948f75906ddf647db1df31f18"
-  integrity sha1-+2zhI/niCtlI91kG3fZH2x3zHxg=
-
 react-loadable-ssr-addon@^0.1.6:
   version "0.1.6"
   resolved "https://registry.yarnpkg.com/react-loadable-ssr-addon/-/react-loadable-ssr-addon-0.1.6.tgz#de3e45f2b3876dc7b9afae19138370f0588b7300"
@@ -11003,13 +11003,6 @@ react-loadable@^5.5.0:
   dependencies:
     prop-types "^15.5.0"
 
-react-perimeter@^0.4.0:
-  version "0.4.0"
-  resolved "https://registry.yarnpkg.com/react-perimeter/-/react-perimeter-0.4.0.tgz#be86b5560bb96650272aaf7bd37639460b82645b"
-  integrity sha512-hSjth5oh4L/ZVR6PfR9eu7B1lil0AteGXLn7ki7YNJI7bkKlZf28pwFyFKNIXkoRJT3FiD01kGYkAmIz1k8b9A==
-  optionalDependencies:
-    react-listener-provider "^0.2.0"
-
 react-router-config@^5.0.0:
   version "5.0.0"
   resolved "https://registry.yarnpkg.com/react-router-config/-/react-router-config-5.0.0.tgz#3d7e298dc64479bf9e1cc77080b8778e9a8d966c"