Realisation Queue on js

Queue.js

class Queue extends Array {
    constructor (STACKSIZE = Number.MAX_SAFE_INTEGER, ...arg) {
        super(...arg)

        Object.defineProperty(this, 'STACKSIZE', {
            value: STACKSIZE
        })

        this.enqueue = this.enqueue.bins(this);
        this.dequeue = this.dequeue.bind(this);
    }

    enqueue() {
        if(this.length >= this.STACKSIZE) {
            let error = new Error("Queue overflow\n");
            error.name = 'Queue Error';

            return error.toString();
        }

        return super.unshift(item);
    }

    dequeue() {
        if(this.length <= 0) {
            let error = new Error("Queue underflow\n");
            error.name = 'Queue Error';

            return error.toString();
        }

        return this.splice(-1,1);
    }
}