How to wait until subscribe event finished?

ionic-v1
1

on car.ts component.
I call simulate.ts’s function
and want to return car_array value from simulate.ts…
but when I console.log on car.ts this.simulate.getCars(lat,lng), it is undefined…

car.ts

 getCars(lat,lng){
console.log(this.simulate.getCars(lat.lng)
return this.simulate.getCars(lat,lng)
}

simulate.ts

getCars(lat,lng){
   this.items = this.afd.list('/employees/Available/', { preserveSnapshot: true });
    
    this.items.subscribe(snapshots=>{
       do some works.....
      ......
       ..this.array_car.push(some value)
     return this.array_car
  }
}