javascript - Merge an interface and new key:value object for function parameter -

i have list of firebase objects search through , want various things object. problem facing fact firebase returns more complex object want have in interface. interface called placeonmap , looks this:

export interface location {   address: string,   latitude: number,   longitude: number } 

the function want call should ideally this:

addplaceonmap(mappoint: { $key: string, placeonmap } ) {   this.placeonmapids.push(mappoint.$key);   this.newplaceonmap.next(mappoint.lat, mappoint.lng);   this.uploadtofirebase(mappoint.$key, {      name: mappoint.address,      lat: mappoint.lat,      lng: mappoint.lng    }); } 

the point being, want combine $key receive firebase keys interface placeonmap has.

for completeness, stored object receive firebase looks this:

{   address: string,   latitude: number,   longitude: number,   street: string,   country: string,   description: string } 

i think use typescript's union not clean want since expect receive this. know create new interface seems me overkill since use once.

if there no other way, resort any or using 2 parameters (probably former).