no-component-method-except-lifecycle

Disallow non-lifecycle methods on @Component. Allowed lifecycle methods are derived from implements (properties are allowed).

• ⭐️ This rule is included in plugin:@rdlabo/rules/recommended preset.

Keep @Component classes thin. Behavior belongs on ViewModel (or modal launch* helpers).

Allowed methods are only those that match lifecycle interfaces listed in implements. A lifecycle method without the corresponding interface is also an error.

Properties are out of scope, including arrow-function fields such as readonly open = () => .... Getters / setters and constructor are allowed.

@Directive / @Injectable / plain classes are not checked. Pair with @rdlabo/rules/require-viewmodel and @rdlabo/rules/implements-ionic-lifecycle.

Existing apps often have many Component methods. Prefer starting with "warn", then move logic to ViewModel before flipping to "error".

Rule Details

✅ Correct: methods match implements

@Component({ selector: 'app-example', template: '' })
export class ExamplePage implements ViewWillEnter, ViewWillLeave, OnDestroy {
  readonly vm = new ViewModel(this);
  readonly open = () => launchOtherPage(this.helper, {});

  constructor() {}

  ionViewWillEnter() {
    this.vm.reload$.next();
  }

  ionViewWillLeave() {}

  ngOnDestroy() {}
}

❌ Incorrect: lifecycle method without implements

@Component({ selector: 'app-example', template: '' })
export class ExamplePage {
  ionViewWillEnter() {} // error — needs implements ViewWillEnter
  ngOnDestroy() {} // error — needs implements OnDestroy
}

❌ Incorrect: implemented interface does not cover the method

@Component({ selector: 'app-example', template: '' })
export class ExamplePage implements ViewWillEnter {
  ionViewWillEnter() {}
  ionViewWillLeave() {} // error — needs implements ViewWillLeave
}

❌ Incorrect: arbitrary methods on Component

@Component({ selector: 'app-example', template: '' })
export class ExamplePage implements ViewWillEnter {
  ionViewWillEnter() {}

  open() {
    // error
    launchOtherPage(this.helper, {});
  }
}

Interface → method mapping

Angular

Ionic

Also allowed (not reported): constructor, get / set accessors, and all properties.

Options

{
  // Extra method names to allow (e.g. trackBy helpers during migration).
  additionalAllowedMethods?: string[];
}

'@rdlabo/rules/no-component-method-except-lifecycle': [
  'warn',
  { additionalAllowedMethods: ['trackById'] },
],

Implementation

• Rule source
• Test source