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Angular6-hmr开发配置

农星华
2023-12-01
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。

创建HMR的环境

在environments文件夹中新建  src/environments/environment.hmr.ts,内容分别配置为:
export const environment = {
production: false,
hmr: true
};
将  src/environments/environment.prod.ts 中 设置属性 hmr: false ,
export const environment = {
production: true,
hmr: false
};
将  src/environments/environment.ts 中 设置属性 hmr: false ,
export const environment = {
production: false,
hmr: false
};
 将angular.json文件中配置HMR环境,并在构建和服务中添加配置以启用HMR。
   Tip:<project-name>这里表示在angular.json中添加此配置的项目的名称。
  " 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 "
      }
    }
  }
在  src/tsconfig.app.json中添加types必要的类型
{
  ...
  " compilerOptions ": {
    ...
    " types ": [ " node "]
  },
}
在终端中执行以下命令,即可将项目以hmr环境运行
ng serve --configuration hmr
或者在package.json文件中添加script对象,用来便捷启动程序:
" scripts ": {
  ...
  " hmr ": " ng serve --configuration hmr "
}

添加@ angurlarclass/HMR依赖

为了使HMR工作,我们需要安装依赖项并配置我们的应用程序来使用它,
$ npm install --save-dev @angularclass/hmr
创建  src/hmr.ts文件, 内容如下:
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();
  });
};
将原 src/main.ts中的内容替换如下,hmr就可以正常工作啦!!! :
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));
}

以上步骤配置完成,终端执行hmr命令,

$ npm run hmr
当在控制台中看到以下提醒时,说明hmr已经在工作啦~!
NOTICE Hot Module Replacement (HMR) is enabled for the dev server.
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