angular-cn/aio/content/guide/ivy.md

Opting into Angular Ivy with Angular CLI

Ivy is the code name for Angular's next-generation compilation and rendering pipeline. Starting with Angular version 8, you can choose to opt in to start using Ivy now, and help in its continuing develpment and tuning.

Starting a new project using Ivy

To start a new project with Ivy enabled, use the --enable-ivy flag with the ng new command:

ng new shiny-ivy-app --enable-ivy

The new project is automatically configured for Ivy.

• The enableIvy option is set to true in tsconfig.app.json.
• The "aot": true option is added to your default build options.

{@a updating}

Updating an existing project to use Ivy

You can update an existing project to use Ivy by making the following configuration changes.

• Add the enableIvy option in the angularCompilerOptions in your project's tsconfig.app.json.

{
  "compilerOptions": { ... },
  "angularCompilerOptions": {
    "enableIvy": true
  }
}

• Set "module": "esnext" inside compilerOptions in your tsconfig.json to support the ES import() statement.

{
  "compilerOptions": {
    ...
    "module": "esnext",
  }
}

• Update your lazy routes to use the import() statement. You can use angular-lazy-routes-fix to automatically transform them.

const routes: Routes = [{
  path: 'lazy',
  // The string syntax for loadChildren is not supported in Ivy:
  //   loadChildren: './lazy/lazy.module#LazyModule'
  // Instead use the import statement:
  loadChildren: () => import('./lazy/lazy.module').then(m => m.LazyModule)
}];

• In the angular.json workspace configuration file, set the default build options for your project to always use AOT compilation.

{
  "projects": {
    "my-existing-project": {
      "architect": {
        "build": {
          "options": {
            ...
            "aot": true,
          }
        }
      }
    }
  }
}

Switching back to the current compiler

To stop using the Ivy compiler you need to undo the steps taken when updating to use Ivy.

• Set enableIvy to false in tsconfig.app.json, or remove it completely.
• Add "experimentalImportFactories": true to your default build options in angular.json to support the import statement in loadChildren outside Ivy.
• Remove "aot": true from your default build options if you didn't have it there before.