Angular Lifecycle Debugging Logger

Decorator to quickly add logging for Angular lifecycle hooks in your components

Minimal markup - no more adding console logs to see what your components are doing!

Installation

npm install --save-dev ng-lifecycle-debug

Usage

import { DebugLifeCycle } from 'ng-lifecycle-debug';

@DebugLifeCycle()
@Component({
  selector: 'app-sheep-stacker',
  templateUrl: './sheep-stacker.component.html',
  styleUrls: ['./sheep-stacker.component.scss']
})
export class SheepStackerComponent implements OnInit, OnChanges {

  @Input() initialStack: number;
  private initialStack$: BehaviorSubject<number>;
  sheepCount$: Observable<number>;

  public ngOnInit(): void {
    this.initialStack$ = new BehaviorSubject<number>(this.initialStack);
    this.sheepCount$ = this.initialStack$.asObservable().pipe(
      switchMap((count) => interval(1000).pipe(map((val) => val + count)))
    );
  }

  public ngOnChanges(changes: SimpleChanges): void {
    if (changes['initialStack'] && !isNaN(+changes['initialStack'].currentValue)) {
      this.initialStack$ && this.initialStack$.next(changes.initialStack.currentValue);
    }
  }

}

// -- Console Output --
// ngOnChanges called for SheepStackerComponent
//    initialStack changed from undefined to 1
// ngOnInit called for SheepStackerComponent
// ngAfterViewInit called for SheepStackerComponent

@DebugLifeCycle('ngOnInit')
// -- Console Output --
// ngOnInit called for SheepStackerComponent

@DebugLifeCycle(['ngOnInit','ngAfterViewInit'])
// -- Console Output --
// ngOnInit called for SheepStackerComponent
// ngAfterViewInit called for SheepStackerComponent

@DebugLifeCycle((hook, className) => console.log(`Awesome ${hook} happened in ${className}`))
// -- Console Output --
// Awesome ngOnChanges happened in SheepStackerComponent
// Awesome ngOnInit happened in SheepStackerComponent
// Awesome ngAfterViewInit happened in SheepStackerComponent

@DebugLifeCycle({hooks: ['ngOnInit','ngAfterViewInit'], logFunc: (hook, className) => console.log(`Awesome ${hook} happened in ${className}`)})
// -- Console Output --
// Awesome ngOnInit happened in SheepStackerComponent
// Awesome ngAfterViewInit happened in SheepStackerComponent

@DebugLifeCycle({hooks: ['ngOnInit','ngAfterViewInit'], logFuncMap: { ngOnInit: () => console.log('Something happened')}})
// -- Console Output --
// Something happened
// ngAfterViewInit called for SheepStackerComponent

Options

Defaults

Default options are to log the ngOnInit, ngOnChanges, ngAfterViewInit, and ngOnDestroy lifecycle hooks using a simple console.log, with a more advanced version using console.group for ngOnChanges.

Simple Options

The decorator accepts simplified options for quicker and more limited use:

| Option | Description | | ----------------- | -------------------------------------------- | | string | log a specific lifecycle hook | | string[] | log a specific subset of lifecycle hooks | | function | a function to use for all logging |

Note that the default function map (that has a different output for ngOnChanges) is still used if a function is given as a single argument. To override this, use the advanced options with logFunc and pass an empty object as the logFuncMap.

Advanced Options

Options are passed as an object with one or more of the following keys:

| Option | Description | | --------------------- | ------------------------------------------------------------- | | hooks: string[] | array of Angular lifecycle hooks to respond to | | logFunc: Function | specify a custom function for each hook | | logFuncMap: Object | specify different functions for different lifecycle hooks, where the object key is the hook and the value is the function | | useMap: boolean | whether or not to use the function map |

Note: the default function map (that has a different output for ngOnChanges) is still used if a function is given as a single argument. For overriding it when

Option Types and Interfaces

| Type / Interface | Description | | ----------------------------- | ------------------------------------------------------- | | DebugLifeCycleHook | String values for Angular lifecycle hooks | | DebugLogFunction | Function required for logging (hook, class, ...args) | | DebugLogFunctionMap | Object for lifecycle hook to function map | | DebugLifeCycleOptionObject | Overall configuration object |

To Do

• Add optional logging of component properties
• Add capability for enter / exit logging