本文介绍了详解Angular5/Angular6项目如何添加热更新(HMR)功能，分享给大家，具体如下：

A：什么是HMR？

Q：HMR（热替换）用于在运行的应用程序中更新代码而不需要重建它。这将导致更快的更新和更少的全页重新加载。

angular6-hmr

提供angular6以上HMR(热更新)功能

步骤

1、进入angular项目父级目录内

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

angular6-hmr目录与angular项目(例如：my-app)是同级关系

2、执行gulp hmr --dir angular目录名

如：

npm i
gulp hmr --dir my-app

3、进入angular项目目录，安装@angularclass/hmr

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

4、这样angular项目的HMR就配置完成了，执行

npm run hmr

注：保持项目名(package.json中的name)与项目目录名一致

以下为手动配置步骤

Angular6添加HMR

environments目录

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

export const environment = {
 hmr: false
};

复制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"

安装依赖

npm install --save-dev @angularclass/hmr

src目录下创建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));
}

Angular5添加HMR

environments目录

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

export const environment = {
 hmr: false
};

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

export const environment = {
 hmr: true
};

.angular-cli.json的environments中添加

"hmr": "environments/environment.hmr.ts"

在package.json的scripts中增加

"hmr": "ng serve --hmr -e=hmr --open"

安装依赖

npm install --save-dev @angularclass/hmr

src目录下创建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));
}