Migration to output function

Angular introduced an improved API for outputs in v17.3 that is considered production ready as of v19. This API mimics the input() API but is not based on Signals. Read more about custom events output function and its benefits in the dedicated guide.

To support existing projects that would like to use output function, the Angular team provides an automated migration that converts @Output custom events to the new output() API.

Run the schematic using the following command:

ng generate @angular/core:output-migration

What does the migration change?

1. @Output() class members are updated to their output() equivalent.
2. Imports in the file of components or directives, at Typescript module level, are updated as well.
3. Migrates API calls like event.next(), whose use is not recommended, to event.emit() and removes event.complete() calls.

Before

import {Component, Output, EventEmitter} from '@angular/core';

@Component({
  template: `<button (click)="someMethod('test')">emit</button>`,
})
export class MyComponent {
  @Output() someChange = new EventEmitter<string>();

  someMethod(value: string): void {
    this.someChange.emit(value);
  }
}

After

import {Component, output} from '@angular/core';

@Component({
  template: `<button (click)="someMethod('test')">emit</button>`,
})
export class MyComponent {
  readonly someChange = output<string>();

  someMethod(value: string): void {
    this.someChange.emit(value);
  }
}

Configuration options

The migration supports a few options for fine tuning the migration to your specific needs.

--path

If not specified, the migration will ask you for a path and update your whole Angular CLI workspace. You can limit the migration to a specific sub-directory using this option.

--analysis-dir

In large projects you may use this option to reduce the amount of files being analyzed. By default, the migration analyzes the whole workspace, regardless of the --path option, in order to update all references affected by an @Output() migration.

With this option, you can limit analysis to a sub-folder. Note that this means that any references outside this directory are silently skipped, potentially breaking your build.

Use these options as shown below:

ng generate @angular/core:output-migration --path src/app/sub-folder

Exceptions

In some cases, the migration will not touch the code. One of these exceptions is the case where the event is used with a pipe() method. The following code won't be migrated:

export class MyDialogComponent {
  @Output() close = new EventEmitter<void>();
  doSome(): void {
    this.close.complete();
  }
  otherThing(): void {
    this.close.pipe();
  }
}