热模块替换正在重新加载整个应用程序而不是特定组件

Question

我创建了一个新的角度项目并设置了HMR,如下所述:https: //github.com/angular/angular-cli/wiki/stories-configure-hmr

该项目包含主要组件(父级),它包含router-outlet3个延迟加载的子组件并链接到该组件.

注意:我也使用自定义,RouteReuseStrategy但就我测试而言,它对HMR没有影响.

无论我正在更改什么文件 - .html或.ts(父/子),整个应用程序都会重新加载.

我已经设置了一个基本的回购,可以在这里找到:https: //github.com/ronfogel/demo-hmr

Answer 1

这种行为是预期的,我将尝试解释发生了什么.

angular已设置的热模块替换实际上只是以更通用的方式重新引导整个应用程序并支持多个应用程序根,但如果您将抽象放在其简单删除app-root标记旁边,再次添加它并再次引导AppModule,那么整个应用程序更改:

export const hmrBootstrap = (
  // webpack stuff
  module: any,
  // bootstrap is AppModule bootstrapper 
  bootstrap: () => Promise<NgModuleRef<any>>
) => {
  let ngModule: NgModuleRef<any>;
  module.hot.accept();
  // bootstraps AppModule ecery time a HMR is needed
  // sets ngModule equal to AppModule if successful (unnecessary)
  bootstrap().then(mod => (ngModule = mod));
  module.hot.dispose(() => {
    // next two lines get native element for all `app-root` tags
    // that exist in `index.html`
    const appRef: ApplicationRef = ngModule.injector.get(ApplicationRef);
    const elements = appRef.components.map(c => c.location.nativeElement);
    // I will share createNewHosts code below it's nothing fancy just
    // the simple add and delete i mentioned
    const makeVisible = createNewHosts(elements);
    //destroy the current AppModule and finalize deletion
    ngModule.destroy();
    makeVisible();
  });
};

Answer 2

这就是我用于最新Angular的功能，效果很好。你可以试试看...

// main.ts
import { bootloader, createInputTransfer, createNewHosts, removeNgStyles } 
    from '@angularclass/hmr/dist/helpers'; // For correct treeshaking

if (environment.production) {
  enableProdMode();
}

type HmrModule<S> = { appRef: ApplicationRef }
type HmrNgrxModule<S, A> = HmrModule<S> & { 
  store: { dispatch: (A) => any } & Observable<S>,
  actionCreator: (s: S) => A
}

const isNgrxModule = <S, A, M extends HmrNgrxModule<S, A>>
  (instance: HmrModule<S> | HmrNgrxModule<S, A>): instance is M =>
    !!((<M>instance).store && (<M>instance).actionCreator);

function processModule<S, A, M extends HmrModule<S> | HmrNgrxModule<S, A>>(ngModuleRef: NgModuleRef<M>) {

  const hot = module['hot'];
  if (hot) {

    hot['accept']();

    const instance = ngModuleRef.instance;
    const hmrStore = hot['data'];

    if (hmrStore) {
      hmrStore.rootState 
        && isNgrxModule(instance) 
        && instance.store.dispatch(instance.actionCreator(hmrStore.rootState));
      hmrStore.restoreInputValues && hmrStore.restoreInputValues();
      instance.appRef.tick();
      Object.keys(hmrStore).forEach(prop => delete hmrStore[prop]);
    }

    hot['dispose'](hmrStore => {
      isNgrxModule(instance) && instance.store.pipe(take(1)).subscribe(s => hmrStore.rootState = s);
      const cmpLocation = instance.appRef.components.map(cmp => cmp.location.nativeElement);
      const disposeOldHosts = createNewHosts(cmpLocation);
      hmrStore.restoreInputValues = createInputTransfer();
      removeNgStyles();
      ngModuleRef.destroy();
      disposeOldHosts();
    });
  }
  else {
    console.error('HMR is not enabled for webpack-dev-server!');
    console.log('Are you using the --hmr flag for ng serve?');
  }

  return ngModuleRef;
}

const bootstrap = () => platformBrowserDynamic().bootstrapModule(AppModule);
const hmrBootstrap = () => bootloader(() => bootstrap().then(processModule));

environment.hmr
  ? hmrBootstrap()
  : bootstrap();

// app.module.ts
@NgModule({ ... })
export class AppModule {
  constructor(public appRef: ApplicationRef) { ... }
}

HMR如果您喜欢这种东西，该设置也将与Ngrx store一起使用。不过，您可以省略Ngrx处理代码。

希望这有所帮助 ：-）