热模块替换(HMR)是一种WebPack功能,用于更新正在运行的应用程序中的代码而无需重建它。这样可以加快更新速度并减少整页重新加载。
为了让HMR使用Angular CLI,我们首先需要添加一个新环境并启用它。
1.HMR添加依赖项并配置app
1 $ npm install --save-dev @ angularclass / hmr
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 import { NgModuleRef, ApplicationRef } from '@angular/core'; import { createNewHosts } from '@angularclass/hmr'; export const hmrBootstrap = (module: any, bootstrap: () => Promise<NgModuleRef<any>>) => { let ngModule: NgModuleRef<any>; module.hot.accept(); bootstrap().then(mod => ngModule = mod); module.hot.dispose(() => { const appRef: ApplicationRef = ngModule.injector.get(ApplicationRef); const elements = appRef.components.map(c => c.location.nativeElement); const makeVisible = createNewHosts(elements); ngModule.destroy(); makeVisible(); }); };
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 import { enableProdMode } from '@angular/core'; import { platformBrowserDynamic } from '@angular/platform-browser-dynamic'; import { AppModule } from './app/app.module'; import { environment } from './environments/environment'; import { hmrBootstrap } from './hmr'; if (environment.production) { enableProdMode(); } const bootstrap = () => platformBrowserDynamic().bootstrapModule(AppModule); if (environment.hmr) { if (module[ 'hot' ]) { hmrBootstrap(module, bootstrap); } else { console.error('HMR is not enabled for webpack-dev-server!'); console.log('Are you using the --hmr flag for ng serve?'); } } else { bootstrap().catch(err => console.log(err)); }
2.配置HMR环境变量 创建一个src/environments/environment.hmr.ts使用以下内容调用的文件:
1 2 3 4 export const environment = { production: false, hmr: true };
更新src/environments/environment.prod.ts并将hmr: false标志添加到环境中:
1 2 3 4 export const environment = { production: true, hmr: false };
更新src/environments/environment.ts并将hmr: false标志添加到环境中:
1 2 3 4 export const environment = { production: false, hmr: false };
接下来,配置angular.json,此处 <project-name>
为你的项目名称;
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 { ... "projects":{ ... "build":{ ... "configurations":{ ... "hmr": { "fileReplacements": [{ "replace": "src/environments/environment.ts", "with": "src/environments/environment.hmr.ts" }] } }, "serve":{ ... "configurations":{ ... "hmr": { "hmr": true, "browserTarget": "<project-name>:build:hmr" } } } } }
修改src/tsconfig.app.json
1 2 3 4 5 6 7 { ... "compilerOptions": { ... "types": ["node"] }, }
我们可以在pack.json中做以下配置方便我们在实际开发中更好的工作,这里使用4205端口,是方便我们启动多个项目时,防止端口重复,可以根据自己的需要具体修改配置,以下仅供参考;
1 2 3 4 "scripts": { ... "hmr": "ng serve --configuration hmr --open --port 4205" },