abstract-value-accessor.ts

export abstract class AbstractValueAccessor<T> implements ControlValueAccessor {

    _value: T = '';
    get value(): T { return this._value; };
    set value(v: T) {
      if (v !== this._value) {
        this._value = v;
        this.onChange(v);
      }
    }

    writeValue(value: T) {
      console.log('wrrite value', value); 
      this._value = value;
       this.onChange(value);
    }

    onChange = (_) => {};
    onTouched = () => {};
    registerOnChange(fn: (_: any) => void): void { this.onChange = fn; }
    registerOnTouched(fn: () => void): void { this.onTouched = fn; }
    
}