Array/List length is zero but Array is not empty

Question

When I console.log my array it shows that the length is zero. I checked that it was an array using Array.isArray which returned true. Also printed out the array values to make sure they exist and it shows in the console:

[]
0: "a"
1: "b"
2: "c"
3: "d"
length: 4
__proto__: Array(0)

I see that __proto__: Array(0) and I'm assuming this means it's a 0 length Array but how do I make it non-zero length so that I can iterate through it?

A thought I had is that this function might be asynchronous but I'm not really sure how to work around that.

Code for reference:

var list=[]
//getting data from a database
snapshot.forEach(function (node) {
   list.push(node.val())
   console.log(node.val()) //values print out
})
console.log(list) //array is length zero

I'm basically trying to add a for loop after this code to read through each value and use it for something else. However I can't iterate through the array because it registers as empty.

Answer 1

For anyone else who is facing similar issue:

You are very likely populating the array within an asynchronous function.

function asyncFunction(list){
 setTimeout(function(){
    list.push('a');
    list.push('b');
    list.push('c');
    console.log(list.length); // array length is 3 - after two seconds
 }, 2000); // 2 seconds timeout
}

var list=[];
//getting data from a database
asyncFunction(list);
console.log(list.length) //array is length zero - after immediately
console.log(list) // console will show all values if you expand "[]" after two seconds

Answer 2

I had the same problem and when I logged the variable snapshot as shown below the variable was logged after most of the logic after it was executed, since it was available later, that is why the Array values are not accessible.

let admins = []
adminRef.once('value',(snapshot)=>{
   console.log(snapshot);
   snapshot.forEach(data=>{
   admins.push(data.key); 
 })
 })

So changed it so that the logic underneath was executed once the snapshot variable was available

 adminRef.once('value',(snapshot)=>{
        if(snapshot){
            console.log(snapshot);
            snapshot.forEach(data=>{
            admins.push(data.key); 
        })}