ListBucket

example.js

var test = new ListBucket(4);

test.push(1);
test.push(2);
test.push(3);
test.push(4);
test.push(5);
test.push(6);
test.push(7);
test.push(8);
test.push(9);
test.push(1);
test.push(2);
test.push(3);
test.push(4);
test.push(5);
test.push(6);
test.push(7);
test.push(8);
test.push(9);
test.push(9);

console.log(test.toArray()); // [ 7, 8, 9, 9 ]
console.log(test); // { array: [ 8, 9, 9, 7 ], position: 3, size: 4, length: 4 }

ListBucket.js

'use strict';

function ListBucket(size) {
    this.array = [];
    this.position = 0;
    this.size = size;
    this.length = 0;
}

ListBucket.prototype.toArray = function () {
    if (this.position === 0) {
        return this.array.slice();
    }

    return this.array.slice(this.position, this.length).concat(
        this.array.slice(0, this.position)
    );
};

ListBucket.prototype.push = function (value) {
    if (this.length < this.size) {
        this.array.push(value);
        this.length++;
        this.position++;
        return;
    }

    if (this.position >= this.length) {
        this.position = 0;
        this.array[this.position] = value;
        this.position++;
        return;
    }

    this.array[this.position] = value;
    this.position++;
};

module.exports = ListBucket;