Saving array of data to Firebase with Javascript/NodeJs -

i need save data database @ index. tried pulling data down with

var people = []; ref.once('value', function(snapshot) {             snapshot.foreach(function(childsnapshot) {                 var id = childsnapshot.key;                 childsnapshot.foreach(function(lastsnapshot) {                     var qr = lastsnapshot.val();                     people.push({[id]: qr});                     return true;                  });                             }); 

my firebase structure:

people: {     jake: "231",     jessica: "412",     rachel: "112" } 

then splice list , add @ index:

index = 1; // add person after jessica people.splice(index, 0, person); 

i want sync firebase set , update don't allow format this.

how can this? thanks!