Please, give me a help for a challenge

The challenge is:
Coding Interview Prep > Data Structures > Create a Priority Queue Class

My code is:

function PriorityQueue () {
  this.collection = [];
  this.printCollection = function() {
    console.log(this.collection);
  };
  // Only change code below this line
  this.enqueue = function(arr) {
        if (this.collection.length === 0) {
            this.collection.push(arr);
        } else {
            let inserted = false;
            for (let i = 0; i <= this.collection.length-1; i++) {
                if (this.collection[i][1] > arr[1]) {
                    this.collection.splice(i, 0, arr);
                    inserted = true;
                    break;
                }
            }
            if (inserted == false) {
                this.collection.push(arr);
            }
        }
    }
    this.dequeue = function() {
        return this.collection.shift();
    }
    this.size = function() {
        return this.collection.length;
    }
    this.front = function() {
        return this.collection[this.collection.length-1];
    }
    this.isEmpty = function() {
        return (this.collection.length === 0);
    }
  // Only change code above this line
}

// tests
  let pq = new PriorityQueue;
  pq.enqueue(["gialbo", 3]);
  pq.enqueue(["peccanza", 1]);
  pq.enqueue(["limonds", 4]);
  pq.enqueue(["forrettini", 2]);
  pq.enqueue(["gualuap", 5]);
  pq.printCollection()
  let d = pq.dequeue();
  let f = pq.front();
  console.log("d = ", d, " f = ", f);
  console.log("size = ", pq.size(), " is empty =",pq.isEmpty());

It seems to me that the tests I put at the bottom of the code give correct results, but the system tests return the following errors

The front method should return the correct item at the
front of the queue as items are enqueued and dequeued.
The priority queue should return items with a higher
priority before items with a lower priority and return
items in first-in-first-out order otherwise.

The thing is, maybe I can’t understand what the challenge is asking.

I believe the front method should return the element/item at the front of the queue. Right now you are returning the array that holds both the element and the priority. I believe this same principle also applies to the other methods that return elements/items (e.g. dequeue).

Also, I think the front of the queue means the element that would be dequeued next based on both priority and position.