本文介紹了詳解Angular5/Angular6項目如何添加熱更新(HMR)功能，分享給大家，具體如下：

A：什么是HMR？

Q：HMR（熱替換）用于在運行的應用程序中更新代碼而不需要重建它。這將導致更快的更新和更少的全頁重新加載。

angular6-hmr

提供angular6以上HMR(熱更新)功能

步驟

1、進入angular項目父級目錄內

git clone https://github.com/staven630/angular6-hmr

angular6-hmr目錄與angular項目(例如：my-app)是同級關系

2、執行gulp hmr --dir angular目錄名

如：

npm igulp hmr --dir my-app

3、進入angular項目目錄，安裝@angularclass/hmr

npm install --save-dev @angularclass/hmr --registry https://registry.npm.taobao.org

4、這樣angular項目的HMR就配置完成了，執行

npm run hmr

注：保持項目名(package.json中的name)與項目目錄名一致

以下為手動配置步驟

Angular6添加HMR

environments目錄

environments.ts和environment.prod.ts增加hmr: false

export const environment = { hmr: false};

復制environment新增environment.hmr.ts修改hmr:true

export const environment = { hmr: true};

.angular.json文件

build的configurations中添加

"hmr": { "fileReplacements": [  {   "replace": "src/environments/environment.ts",   "with": "src/environments/environment.hmr.ts"  } ]}

serve的configurations中添加

"hmr": { "hmr": true, "browserTarget": "my-app:build:hmr"}

tsconfig.app.json的compilerOptions的types中添加

"types": ["node"]

package.json的scripts中添加

"hmr": "ng serve --configuration hmr --open"

安裝依賴

npm install --save-dev @angularclass/hmr

src目錄下創建hmr.ts

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(); });};

修改main.ts

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));}