So I have this function:

export const getLastMsg = (user, convoid) => {
  let item = []
   user &&  db.collection('chats').doc(convoid).collection('messages').orderBy('date', 'desc').limit(1).onSnapshot(snap=> {
    let items = []
    snap.forEach(doc => items.push(doc.data())) 
    item = items[0]
  }) 
}

When I call this function in my app, i get undefined, but when i console log the value inside the snapshot i get the value. Any Idea how I can make this function return the value?