Simple implementation of a Queue in JavaScript - with performance tests

queue.js

/**
 * ============================================
 * CUSTOM IMPLEMENTATION OF QUEUE CLASS
 * ============================================
 */

/**
 * Implementation of Queue.
 */
class Queue {
    /**
     * Create a queue.
     */
    constructor () {
        this.store = {};
        this.front = 0;
        this.end = 0;
    }
}

/**
 * Add item to end of queue.
 * @param {*} The data to store in the position.
 */
Queue.prototype.enqueue = function (data) {
    this.store[this.end] = data;
    this.end++;
};

/**
 * Remove item from queue and return its data.
 * @return {*} The data stored in item.
 */
Queue.prototype.dequeue = function () {
    if (this.front === this.end) return null;

    const data = this.store[this.front];
    delete this.store[this.front];
    this.front++;
    return data;
};

/**
 * Return current size of queue.
 * @return {number} Size of queue.
 */
Queue.prototype.size = function () {
    return this.end - this.front;
};

/**
 * Return item at front of queue without dequeueing.
 * @return {*} The data stored in item.
 */
Queue.prototype.peek = function () {
    if (this.size() === 0) return null;
    return this.store[this.front];
};


/**
 * ============================================
 * PERFORMANCE TESTING (SPEED)
 * ============================================
 * Tests by enqueuing `iterations` number of items
 * and dequeueing for every multiple of 10.
 */
// Comment out and test accordingly
// const iterations = 10000;
const iterations = 100000;

// Using Queue class implementation
var t0 = performance.now();
const customQueue = new Queue();
for (var i = 0; i < iterations; i++) {
    customQueue.enqueue(i);
    if (i % 10 === 0) customQueue.dequeue();
}
var t1 = performance.now();
console.log('customQueue performance:', t1 - t0, 'ms');

 
// Using native Array
var t2 = performance.now();
const arrayQueue = [];
for (var j = 0; j < iterations; j++) {
    arrayQueue.push(j);
    if (j % 10 === 0) arrayQueue.shift();
}
var t3 = performance.now();
console.log('arrayQueue performance:', t3 - t2, 'ms');