function with paramater, result return in js

1. var rest = [];
2.  
3. function queryCollection(collection, callback){
4. collection.find({},{'collection':1}).toArray(function(err, result) {
5. if (err) {
6. console.log(err);
7. } else if (result.length > 0) {
8. rest.push(result);
9. callback();
10. }
11. });
12. }
13.  
14. queryCollection(collection, function(){
15. console.log(rest);
16. });

input collection, output rest