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Opting into Angular Ivy with Angular CLI

Starting with Angular version 8 you can opt-in to the new [Angular Ivy compilation and rendering pipeline].

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

Everything will be configured for you:

  • enableIvy set to true in src/
  • "aot": true added to your default build options.
  • postinstall script for the Angular Compatibility Compiler.

{@a updating}

Updating an existing project to use Ivy

By configuring a few key files, you can also update your existing project(s) to use Ivy.

  • Add the allowEmptyCodegenFiles (needed only before version 8 final) and enableIvy options in the angularCompilerOptions in your project's src/
  "compilerOptions": { ... },
  "angularCompilerOptions": {
    "enableIvy": true,
    "allowEmptyCodegenFiles": true,
  • Set the default build options for your project to always use AOT compilation if it isn't already:
  "projects": {
    "my-existing-project": {
      "architect": {
        "build": {
          "options": {
            "aot": true,
  "scripts": {
    "postinstall": "ivy-ngcc"
  • Reinstall your package.json dependencies to run the newly added script:
npm install

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 src/, or remove it completely.
  • Remove "aot": true from your default build options if you didn't have it there before.
  • Remove the postinstall script.
  • Delete and reinstall your node modules.

{@a ngcc}

The Angular Compatibility Compiler

Your third party libraries also need to be compiled with Ivy for you to use them in your Ivy application. That's where the Angular Compatibility (ngcc) compiler comes into play.

We set it as a postinstall script in your package.json so that it always runs when you install your package.json dependencies.

Using a postinstall hook to run ngcc is just a temporary integration. We expect ngcc to be seamlessly integrated into the Angular CLI build pipeline in the future before the full Ivy rollout. Once that's implemented ngcc will not be visible to developers.

Until that happens, opting into Ivy means that all projects in a single CLI workspace will be compiled with Ivy.

Note: we are aware of build-time performance issues with ngcc. Please bear with us while we improve the tooling and build integration in the Angular CLI.

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