JavaScript Obj.length 方法返回 undefined 尽管字典包含元素

Question

I've been working on a project and I'm currently working on a function which dynamically creates a dictionary data structure. The key used is the roll number of the student, and the value is the student's name.

But I'm unable to iterate through this dictionary. I've tried displaying the dictionary on console, but all I could see is an empty dictionary . I could see the elements in it, only if I expand it further . And when I display length using Obj.length on console, it displays 'undefined'.
I've read on other questions that Obj.length only works on arrays(ie, enumerable types), and I've tried using an array instead of a dictionary. In that case, it shows an empty array and would not show values unless I manually expand it. I've also tried Obj.keys() method on the dictionary, and I've encountered the same issue.
This is the function's code:

function dictGenerator(rollnos, selectedValue) {
            var dict = {};
            for(let i = 0; i < rollnos.length; i++) {
                get(child(dbref, "RegisterNos/" + rollnos[i])).then((snapshot)=>{
                    if(Object.keys(snapshot.val()).length-1 == selectedValue){
                        dict[rollnos[i]] = snapshot.val()["name"];
                    }
                });
            }
            console.log(dict);
            console.log(dict.length);
        }
}

Any help on how I could iterate through my dictionary would be appreciated, Thank you.

Edit: code implementation using promises.

function dictGenerator(regnos, selectedValue) {
            const get_dict = async () => {
                var dict = {};
                for(let i = 0; i < regnos.length; i++){
                get(child(dbref, "RegisterNos/" + regnos[i])).then((snapshot)=>{
                    if(Object.keys(snapshot.val()).length-1 == selectedValue){
                        dict[regnos[i]] = snapshot.val()["name"];
                    }
                });
            }
            return dict;
            };

            get_dict().then((dict) => {
                console.log(dict);
            });
        }

Answer 1

Basing on comments made by VALZ and JaredSmith, this is the working code:

function dictGenerator(regnos, selectedValue) {
            const get_dict = async () => {
                var dict = {};
                for(let i = 0; i < regnos.length; i++){
                await get(child(dbref, "RegisterNos/" + regnos[i])).then((snapshot)=>{
                    if(Object.keys(snapshot.val()).length-1 == selectedValue){
                        dict[regnos[i]] = snapshot.val()["name"];
                    }
                });
            }
            return dict;
            };

            get_dict().then((dict) => {
                console.log(dict);
            });
        }
}