Angular Destroyable component decorator

destroyable.decorator.ts

import { Observable } from 'rxjs/Observable';

export function Destroyable() {
  return (target) => {

    const originalOnDestroy: Function = target.prototype.ngOnDestroy;
    // tslint:disable-next-line:only-arrow-functions
    target.prototype.ngOnDestroy = function() {
      if (!('_componentDestroyed$' in this || !(this._componentDestroyed$ instanceof Observable))) {
        throw new Error('Destroyable components must define _componentDestroyed$ property');
      }
      if (this._componentDestroyed$) {
        this._componentDestroyed$.next();
        this._componentDestroyed$.complete();
      }
      this._componentDestroyed$ = null;
      if (originalOnDestroy)
        originalOnDestroy.apply(this, arguments);
    };
  };
}