normal.js

// Retrieve cities from California
db.collection("cities").where("state", "==", "CA")
  .onSnapshot(function(querySnapshot) {
        querySnapshot.forEach(function(doc) {
            // binded to the UI
            allItems.push(doc.data().name);
        });
    });
// Retrieve cities from Colorado
db.collection("cities").where("state", "==", "CO")
    .onSnapshot(function(querySnapshot) {
        var cities = [];
        querySnapshot.forEach(function(doc) {
           // binded to the UI
             allItems.push(cities);
        });
});