fix(react): first render performance improvements

core/src/components/tabs/readme.md

@@ -176,34 +176,30 @@ will match the following tab:
 ### React
 
 ```tsx
+import React from 'react';
+import { IonTabs, IonTabBar, IonTabButton, IonIcon, IonLabel, IonBadge } from '@ionic/react';
+
 export const TabsExample: React.FC = () => (
   <IonTabs>
-  <IonRouterOutlet>
-    <Redirect exact path="/" to="/tabs/schedule" />
-    {/* 
-      Using the render method prop cuts down the number of renders your components will have due to route changes.
-      Use the component prop when your component depends on the RouterComponentProps passed in automatically.        
-    */}
-    <Route path="/tabs/schedule" render={() => <SchedulePage />} exact={true} />
-    <Route path="/tabs/speakers" render={() => <SpeakerList />} exact={true} />
-    <Route path="/tabs/map" render={() => <MapView />} exact={true} />
-    <Route path="/tabs/about" render={() => <About />} exact={true} />
-  </IonRouterOutlet>
     <IonTabBar slot="bottom">
-    <IonTabButton tab="schedule" href="/tabs/schedule">
-      <IonIcon icon={calendar} />
+      <IonTabButton tab="schedule">
+        <IonIcon name="calendar" />
         <IonLabel>Schedule</IonLabel>
+        <IonBadge>6</IonBadge>
       </IonTabButton>
-    <IonTabButton tab="speakers" href="/tabs/speakers">
-      <IonIcon icon={contacts} />
+
+      <IonTabButton tab="speakers">
+        <IonIcon name="contacts" />
         <IonLabel>Speakers</IonLabel>
       </IonTabButton>
-    <IonTabButton tab="map" href="/tabs/map">
-      <IonIcon icon={map} />
+
+      <IonTabButton tab="map">
+        <IonIcon name="map" />
         <IonLabel>Map</IonLabel>
       </IonTabButton>
-    <IonTabButton tab="about" href="/tabs/about">
-      <IonIcon icon={informationCircle} />
+
+      <IonTabButton tab="about">
+        <IonIcon name="information-circle" />
         <IonLabel>About</IonLabel>
       </IonTabButton>
     </IonTabBar>

packages/react-router/src/ReactRouter/IonRouteAction.ts

@@ -0,0 +1 @@
+export type IonRouteAction = 'push' | 'replace' | 'pop';

packages/react-router/src/ReactRouter/NavManager.tsx

@@ -4,11 +4,12 @@ import { Location as HistoryLocation, UnregisterCallback } from 'history';
 import React from 'react';
 import { RouteComponentProps } from 'react-router-dom';
 
+import { IonRouteAction } from './IonRouteAction';
 import { StackManager } from './StackManager';
 
 interface NavManagerProps extends RouteComponentProps {
   onNavigateBack: (defaultHref?: string) => void;
-  onNavigate: (type: 'push' | 'replace', path: string, state?: any) => void;
+  onNavigate: (type: 'push' | 'replace' | 'pop', path: string, state?: any) => void;
 }
 
 export class NavManager extends React.Component<NavManagerProps, NavContextState> {
@@ -24,7 +25,7 @@ export class NavManager extends React.Component<NavManagerProps, NavContextState
       getStackManager: this.getStackManager.bind(this),
       getPageManager: this.getPageManager.bind(this),
       currentPath: this.props.location.pathname,
-      registerIonPage: () => { return; }, // overridden in View for each IonPage
+      registerIonPage: () => { return; } // overridden in View for each IonPage
     };
 
     this.listenUnregisterCallback = this.props.history.listen((location: HistoryLocation) => {
@@ -52,8 +53,8 @@ export class NavManager extends React.Component<NavManagerProps, NavContextState
     this.props.onNavigateBack(defaultHref);
   }
 
-  navigate(path: string, direction?: RouterDirection | 'none', type: 'push' | 'replace' = 'push') {
-    this.props.onNavigate(type, path, direction);
+  navigate(path: string, direction?: RouterDirection | 'none', ionRouteAction: IonRouteAction = 'push') {
+    this.props.onNavigate(ionRouteAction, path, direction);
   }
 
   getPageManager() {

packages/react-router/src/ReactRouter/Router.tsx

@@ -7,6 +7,7 @@ import { RouteComponentProps, matchPath, withRouter } from 'react-router-dom';
 import { generateId, isDevMode } from '../utils';
 import { LocationHistory } from '../utils/LocationHistory';
 
+import { IonRouteAction } from './IonRouteAction';
 import { IonRouteData } from './IonRouteData';
 import { NavManager } from './NavManager';
 import { RouteManagerContext, RouteManagerContextState } from './RouteManagerContext';
@@ -15,15 +16,19 @@ import { ViewStack, ViewStacks } from './ViewStacks';
 
 interface RouteManagerState extends RouteManagerContextState {
   location?: HistoryLocation;
-  action?: HistoryAction;
+  action?: IonRouteAction;
 }
 
 class RouteManager extends React.Component<RouteComponentProps, RouteManagerState> {
   listenUnregisterCallback: UnregisterCallback | undefined;
   activeIonPageId?: string;
-  currentDirection?: RouterDirection;
+  currentIonRouteAction?: IonRouteAction;
+  currentRouteDirection?: RouterDirection;
   locationHistory = new LocationHistory();
-  routes: { [key: string]: any; } = {};
+  routes: { [key: string]: React.ReactElement<any>; } = {};
+  ionPageElements: { [key: string]: HTMLElement; } = {};
+  routerOutlets: { [key: string]: HTMLIonRouterOutletElement; } = {};
+  firstRender = true;
 
   constructor(props: RouteComponentProps) {
     super(props);
@@ -52,7 +57,8 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
   componentDidUpdate(_prevProps: RouteComponentProps, prevState: RouteManagerState) {
     // Trigger a page change if the location or action is different
     if (this.state.location && prevState.location !== this.state.location || prevState.action !== this.state.action) {
-      this.setActiveView(this.state.location!, this.state.action!);
+      const viewStacks = Object.assign(new ViewStacks(), this.state.viewStacks);
+      this.setActiveView(this.state.location!, this.state.action!, viewStacks);
     }
   }
 
@@ -71,10 +77,10 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
     const { view } = viewStacks.findViewInfoById(viewId);
     if (view) {
       view.show = false;
-      view.ionPageElement = undefined;
       view.isIonRoute = false;
       view.prevId = undefined;
       view.key = generateId();
+      delete this.ionPageElements[view.id];
       this.setState({
         viewStacks
       });
@@ -82,23 +88,29 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
   }
 
   historyChange(location: HistoryLocation, action: HistoryAction) {
-    location.state = location.state || { direction: this.currentDirection };
-    this.currentDirection = undefined;
-    if (action === 'PUSH') {
+    const ionRouteAction = this.currentIonRouteAction === 'pop' ? 'pop' : action.toLowerCase();
+    let direction = this.currentRouteDirection;
+
+    if (ionRouteAction === 'push') {
       this.locationHistory.add(location);
-    } else if ((action === 'REPLACE' && location.state.direction === 'back') || action === 'POP') {
+    } else if (ionRouteAction === 'pop') {
       this.locationHistory.pop();
-    } else {
+      direction = direction || 'back';
+    } else if (ionRouteAction === 'replace') {
       this.locationHistory.replace(location);
-    }
-    this.setState({
-      location,
-      action
-    });
+      direction = 'none';
     }
 
-  setActiveView(location: HistoryLocation, action: HistoryAction) {
-    const viewStacks = Object.assign(new ViewStacks(), this.state.viewStacks);
+    location.state = location.state || { direction };
+    this.setState({
+      location,
+      action: ionRouteAction as IonRouteAction
+    });
+    this.currentRouteDirection = undefined;
+    this.currentIonRouteAction = undefined;
+  }
+
+  setActiveView(location: HistoryLocation, action: IonRouteAction, viewStacks: ViewStacks) {
     let direction: RouterDirection | undefined = (location.state && location.state.direction) || 'forward';
     let leavingView: ViewItem | undefined;
     const viewStackKeys = viewStacks.getKeys();
@@ -122,25 +134,18 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
         this.activeIonPageId = enteringView.id;
 
         if (leavingView) {
-          if (direction === 'forward') {
-            if (action === 'PUSH') {
+          if (action === 'push' && direction === 'forward') {
             /**
              * If the page is being pushed into the stack by another view,
              * record the view that originally directed to the new view for back button purposes.
              */
             enteringView.prevId = leavingView.id;
-            } else if (action === 'POP') {
-              direction = leavingView.prevId === enteringView.id ? 'back' : 'none';
-            } else {
-              direction = direction || 'back';
-              leavingView.mount = false;
-            }
-          }
-          if (direction === 'back' || action === 'REPLACE') {
+          } else if (action === 'pop' || action === 'replace') {
             leavingView.mount = false;
             this.removeOrphanedViews(enteringView, enteringViewStack);
           }
-          leavingViewHtml = enteringView.id === leavingView.id ? leavingView.ionPageElement!.outerHTML : undefined;
+
+          leavingViewHtml = enteringView.id === leavingView.id ? this.ionPageElements[leavingView.id].outerHTML : undefined;
         } else {
           // If there is not a leavingView, then we shouldn't provide a direction
           direction = undefined;
@@ -167,16 +172,17 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
       if (shouldTransitionPage) {
         const { view: enteringView, viewStack } = this.state.viewStacks.findViewInfoById(this.activeIonPageId);
         if (enteringView && viewStack) {
-          const enteringEl = enteringView.ionPageElement ? enteringView.ionPageElement : undefined;
-          const leavingEl = leavingView && leavingView.ionPageElement ? leavingView.ionPageElement : undefined;
+          const enteringEl = this.ionPageElements[enteringView.id];
+          const leavingEl = leavingView && this.ionPageElements[leavingView.id];
           if (enteringEl) {
             // Don't animate from an empty view
             const navDirection = leavingEl && leavingEl.innerHTML === '' ? undefined : direction === 'none' ? undefined : direction;
             const shouldGoBack = !!enteringView.prevId;
+            const routerOutlet = this.routerOutlets[viewStack.id];
             this.commitView(
               enteringEl!,
               leavingEl!,
-              viewStack.routerOutlet,
+              routerOutlet,
               navDirection,
               shouldGoBack,
               leavingViewHtml);
@@ -211,12 +217,13 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
         this.removeOrphanedViews(v, viewStack);
 
         // If view is not currently visible, go ahead and remove it from DOM
-        if (v.ionPageElement!.classList.contains('ion-page-hidden')) {
+        const page = this.ionPageElements[v.id];
+        if (page.classList.contains('ion-page-hidden')) {
           v.show = false;
-          v.ionPageElement = undefined;
           v.isIonRoute = false;
           v.prevId = undefined;
           v.key = generateId();
+          delete this.ionPageElements[v.id];
         }
         v.mount = false;
       }
@@ -270,9 +277,9 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
       const prevViewStacks = Object.assign(new ViewStacks(), prevState.viewStacks);
       const newStack: ViewStack = {
         id: stack,
-        views: stackItems,
-        routerOutlet
+        views: stackItems
       };
+      this.routerOutlets[stack] = routerOutlet;
       if (activeId) {
         this.activeIonPageId = activeId;
       }
@@ -286,18 +293,6 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
   }
 
   async setupRouterOutlet(routerOutlet: HTMLIonRouterOutletElement) {
-    const waitUntilReady = async () => {
-      if (routerOutlet.componentOnReady) {
-        routerOutlet.dispatchEvent(new Event('routerOutletReady'));
-        return;
-      } else {
-        setTimeout(() => {
-          waitUntilReady();
-        }, 0);
-      }
-    };
-
-    await waitUntilReady();
 
     const canStart = () => {
       const config = getConfig();
@@ -329,20 +324,13 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
   }
 
   syncView(page: HTMLElement, viewId: string) {
-    this.setState(state => {
-      const viewStacks = Object.assign(new ViewStacks(), state.viewStacks);
+    const viewStacks = Object.assign(new ViewStacks(), this.state.viewStacks);
     const { view } = viewStacks.findViewInfoById(viewId);
-
-      view!.ionPageElement = page;
-      view!.isIonRoute = true;
-
-      return {
-        viewStacks
-      };
-
-    }, () => {
-      this.setActiveView(this.state.location || this.props.location, this.state.action!);
-    });
+    if (view) {
+      view.isIonRoute = true;
+      this.ionPageElements[view.id] = page;
+      this.setActiveView(this.state.location || this.props.location, this.state.action!, viewStacks);
+    }
   }
 
   syncRoute(_id: string, routerOutlet: any) {
@@ -359,6 +347,11 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
   }
 
   private async commitView(enteringEl: HTMLElement, leavingEl: HTMLElement, ionRouterOutlet: HTMLIonRouterOutletElement, direction?: NavDirection, showGoBack?: boolean, leavingViewHtml?: string) {
+    if (!this.firstRender) {
+
+      if (!('componentOnReady' in ionRouterOutlet)) {
+        await waitUntilRouterOutletReady(ionRouterOutlet);
+      }
 
       if ((enteringEl === leavingEl) && direction && leavingViewHtml) {
         // If a page is transitioning to another version of itself
@@ -388,14 +381,28 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
         leavingEl.classList.add('ion-page-hidden');
         leavingEl.setAttribute('aria-hidden', 'true');
       }
+    } else {
+      enteringEl.classList.remove('ion-page-invisible');
+      enteringEl.style.zIndex = '101';
+      this.firstRender = false;
+    }
   }
 
-  handleNavigate(type: 'push' | 'replace', path: string, direction?: RouterDirection) {
-    this.currentDirection = direction;
-    if (type === 'push') {
+  handleNavigate(ionRouteAction: IonRouteAction, path: string, direction?: RouterDirection) {
+    this.currentIonRouteAction = ionRouteAction;
+    switch (ionRouteAction) {
+      case 'push':
+        this.currentRouteDirection = direction;
         this.props.history.push(path);
-    } else {
+        break;
+      case 'pop':
+        this.currentRouteDirection = direction || 'back';
         this.props.history.replace(path);
+        break;
+      case 'replace':
+        this.currentRouteDirection = 'none';
+        this.props.history.replace(path);
+        break;
     }
   }
 
@@ -405,26 +412,26 @@ class RouteManager extends React.Component<RouteComponentProps, RouteManagerStat
       if (leavingView.id === leavingView.prevId) {
         const previousLocation = this.locationHistory.previous();
         if (previousLocation) {
-          this.handleNavigate('replace', previousLocation.pathname + previousLocation.search, 'back');
+          this.handleNavigate('pop', previousLocation.pathname + previousLocation.search);
         } else {
-          defaultHref && this.handleNavigate('replace', defaultHref, 'back');
+          defaultHref && this.handleNavigate('pop', defaultHref);
         }
       } else {
         const { view: enteringView } = this.state.viewStacks.findViewInfoById(leavingView.prevId);
         if (enteringView) {
           const lastLocation = this.locationHistory.findLastLocationByUrl(enteringView.routeData.match!.url);
           if (lastLocation) {
-            this.handleNavigate('replace', lastLocation.pathname + lastLocation.search, 'back');
+            this.handleNavigate('pop', lastLocation.pathname + lastLocation.search);
           } else {
-            this.handleNavigate('replace', enteringView.routeData.match!.url, 'back');
+            this.handleNavigate('pop', enteringView.routeData.match!.url);
           }
         } else {
           const currentLocation = this.locationHistory.previous();
           if (currentLocation) {
-            this.handleNavigate('replace', currentLocation.pathname + currentLocation.search, 'back');
+            this.handleNavigate('pop', currentLocation.pathname + currentLocation.search);
           } else {
             if (defaultHref) {
-              this.handleNavigate('replace', defaultHref, 'back');
+              this.handleNavigate('pop', defaultHref);
             }
           }
         }
@@ -464,5 +471,15 @@ function clonePageElement(leavingViewHtml: string) {
   return newEl.firstChild as HTMLElement;
 }
 
+async function waitUntilRouterOutletReady(ionRouterOutlet: HTMLIonRouterElement) {
+  if ('componentOnReady' in ionRouterOutlet) {
+    return;
+  } else {
+    setTimeout(() => {
+      waitUntilRouterOutletReady(ionRouterOutlet);
+    }, 0);
+  }
+}
+
 export const RouteManagerWithRouter = withRouter(RouteManager);
 RouteManagerWithRouter.displayName = 'RouteManager';

packages/react-router/src/ReactRouter/StackManager.tsx

@@ -13,13 +13,10 @@ interface StackManagerProps {
   children?: React.ReactNode;
 }
 
-interface StackManagerState {
-  routerOutletReady: boolean;
-}
+interface StackManagerState { }
 
 class StackManagerInner extends React.Component<StackManagerProps, StackManagerState> {
   routerOutletEl: React.RefObject<HTMLIonRouterOutletElement> = React.createRef();
-
   id: string;
 
   constructor(props: StackManagerProps) {
@@ -27,18 +24,11 @@ class StackManagerInner extends React.Component<StackManagerProps, StackManagerS
     this.id = this.props.id || generateId();
     this.handleViewSync = this.handleViewSync.bind(this);
     this.handleHideView = this.handleHideView.bind(this);
-    this.state = {
-      routerOutletReady: false
-    };
+    this.state = {};
   }
 
   componentDidMount() {
     this.props.routeManager.setupIonRouter(this.id, this.props.children, this.routerOutletEl.current!);
-    this.routerOutletEl.current!.addEventListener('routerOutletReady', () => {
-      this.setState({
-        routerOutletReady: true
-      });
-    });
   }
 
   static getDerivedStateFromProps(props: StackManagerProps, state: StackManagerState) {
@@ -70,9 +60,7 @@ class StackManagerInner extends React.Component<StackManagerProps, StackManagerS
     const viewStack = routeManager.viewStacks.get(this.id);
     const views = (viewStack || { views: [] }).views.filter(x => x.show);
     const ionRouterOutlet = React.Children.only(this.props.children) as React.ReactElement;
-    const { routerOutletReady } = this.state;
-
-    const childElements = routerOutletReady ? views.map(view => {
+    const childElements = views.map(view => {
       const route = routeManager.getRoute(view.routeId);
       return (
         <ViewTransitionManager
@@ -90,7 +78,7 @@ class StackManagerInner extends React.Component<StackManagerProps, StackManagerS
           </View>
         </ViewTransitionManager>
       );
-    }) : <div></div>;
+    });
 
     const elementProps: any = {
       ref: this.routerOutletEl

packages/react-router/src/ReactRouter/View.tsx

@@ -1,6 +1,5 @@
 import { IonLifeCycleContext, NavContext } from '@ionic/react';
 import React from 'react';
-import { Redirect, Route } from 'react-router-dom';
 
 import { isDevMode } from '../utils';
 
@@ -20,20 +19,6 @@ export class View extends React.Component<ViewProps, {}> {
   context!: React.ContextType<typeof IonLifeCycleContext>;
   ionPage?: HTMLElement;
 
-  componentDidMount() {
-    /**
-     * If we can tell if view is a redirect, hide it so it will work again in future
-     */
-    const { view, route } = this.props;
-    if (route.type === Redirect) {
-      this.props.onHideView(view.id);
-    } else if (route.type === Route && route.props.render) {
-      if (route.props.render().type === Redirect) {
-        this.props.onHideView(view.id);
-      }
-    }
-  }
-
   componentWillUnmount() {
     if (this.ionPage) {
       this.ionPage.removeEventListener('ionViewWillEnter', this.ionViewWillEnterHandler.bind(this));

packages/react-router/src/ReactRouter/ViewItem.ts

@@ -5,10 +5,7 @@ export interface ViewItem<RouteData = any> {
   key: string;
 
   routeId: string;
-  /** The <Route /> or <Redirect /> component associated with the view */
-  // route: React.ReactElement<any>;
-  /** The reference to the <IonPage /> element. */
-  ionPageElement?: HTMLElement;
+
   /** The routeData for the view. */
   routeData: RouteData;
   /** Used to track which page pushed the page into view. Used for back button purposes. */

packages/react-router/src/ReactRouter/ViewStacks.ts

@@ -6,7 +6,6 @@ import { ViewItem } from './ViewItem';
 
 export interface ViewStack {
   id: string;
-  routerOutlet: HTMLIonRouterOutletElement;
   views: ViewItem[];
 }
 

packages/react-router/tslint.json

@@ -30,6 +30,8 @@
     "jsx-wrap-multiline": false,
     "forin": false,
     "strict-type-predicates": false,
-    "no-unused-expression": false
+    "no-unused-expression": false,
+    "no-constant-condition": false,
+    "no-empty-interface": false
   }
 }

packages/react/src/components/navigation/IonTabBar.tsx

@@ -75,7 +75,7 @@ const IonTabBarUnwrapped = /*@__PURE__*/(() => class extends React.Component<Pro
       if (originalHref === currentHref) {
         this.context.navigate(originalHref, 'none');
       } else {
-        this.context.navigate(originalHref, 'back', 'replace');
+        this.context.navigate(originalHref, 'back', 'pop');
       }
     } else {
       if (this.props.onIonTabsWillChange) {

packages/react/src/contexts/NavContext.ts

@@ -5,7 +5,7 @@ export interface NavContextState {
   getPageManager: () => any;
   getStackManager: () => any;
   goBack: (defaultHref?: string) => void;
-  navigate: (path: string, direction?: RouterDirection | 'none', type?: 'push' | 'replace') => void;
+  navigate: (path: string, direction?: RouterDirection | 'none', ionRouteAction?: 'push' | 'replace' | 'pop') => void;
   hasIonicRouter: () => boolean;
   registerIonPage: (page: HTMLElement) => void;
   currentPath: string | undefined;