NGX Mutation

A service that emits changes being made to the DOM tree utilizing Mutation Observer

Demo

Installation

npm install ngx-mutation

Usage

There are two approaches of using ngx-mutation. Both approaches results an Observable<NgxMutationResult>

export interface NgxMutationResult {
  readonly mutation: ReadonlyArray<MutationRecord>;
}

injectNgxMutation()

If you're on Angular 14+ and are using inject() for Dependency Injection, you can use injectNgxMutation() to grab the Observable<NgxMutationResult>

@Component({})
export class SomeComponent {
  readonly mutationResult$ = injectNgxMutation(); // Observable<NgxMutationResult>
}

injectNgxMutation() accepts a Partial<NgxMutationOptions> and will be merged with the default global options.

export interface NgxMutationOptions {
  /* "config" options that is passed in new MutationObserver */
  config: MutationObserverInit;
  /* time in ms to debounce the events; */
  debounce: number;
  /* emit in NgZone or not. Default to "true" */
  emitInZone: boolean;
  /* emit the initial DOMRect of nativeElement. Default to "false" */
  emitInitialResult: boolean;
}

export const defaultMutationOptions: NgxMutationOptions = {
  config: {
    attributes: true,
    characterData: true,
    childList: true,
  },
  debounce: 0,
  emitInZone: true,
  emitInitialResult: false,
};

With Output

Instead of getting the Observable<NgxMutationResult>, you can assign injectNgxMutation() to an Output directly

@Component({})
export class SomeComponent {
  @Output() mutate = injectNgxMutation(); // mutate emits everytime NgxMutation emits
}

<some-component (ngxMutation)="onMutate($event)"></some-component>
<!-- $event is of type NgxMutationResult -->

NgxMutation

If you're not using inject(), you can use the NgxMutation directive

<some-component (ngxMutation)="onMutate($event)"></some-component>
<some-component
  (ngxMutation)="onMutate($event)"
  [ngxMutationOptions]="optionalOptions"
></some-component>

With hostDirectives

With Angular 15, you can also use NgxMutation as a hostDirectives and expose ngxMutation Output

@Component({
  hostDirectives: [{ directive: NgxMutation, outputs: ["ngxMutation"] }],
})
export class SomeComponent {
  @HostListener("ngxMutation", ["$event"])
  onMutate(event: NgxMutationResult) {
    // listen for mutation event from NgxMutation
  }
}

Provide global NgxMutationOptions

You can use provideNgxMutationOptions() to provide global options for a specific Component tree. If you call provideNgxMutationOptions() in bootstrapApplication() (for Standalone) and AppModule (for NgModule) then the options is truly global.

Contributions

All contributions of any kind are welcome.

Thanks

This directive is heavily inspired on the ngx-resize directive by Chau Tran. https://github.com/nartc/ngx-resize