counter.component.ts

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

@Component({
  selector: 'catalog-counter',
  templateUrl: './counter.component.html',
  styleUrls: ['./counter.component.scss'],
  providers: [VALUE_ACCESSOR(CounterComponent)],
})
export class CounterComponent extends ControlValueAccessor {
  @Output()
  valueChange = new EventEmitter<number>();

  @Input()
  value = 0;

  changeValue(value: number) {
    if (this.isZeroOrBigger(value)) {
      this.value = this.value + value;
      this.valueChange.next(this.value);
      this.pushChanges(this.value);
    }
  }

  private isZeroOrBigger(value: number) {
    return this.value + value > -1;
  }
}