SOURCE

    let create_array = function(...element){
        let target = [];
        target.push(...element);

        return new Proxy(target,{
            get(target, p, receiver) {
                let index = Number.parseInt(p);
                if(index<0){
                    index = target.length + index
                }
                return Reflect.get(target, index, receiver)
            }
        })
    }
    let arr = create_array(1,2,3,4);
    console.log(arr[-1]);