Q

A tiny, simple and fast FIFO queue.

• Simple interface
• Up there with the fastest queue libraries
• 252 bytes minzipped
• TypeScript declarations
• Tests and benchmarks
• No dependencies
• Public domain

Installation

Using your package manager of choice, install:

@joakimstai/q

Usage

Importing

Import Q from @joakimstai/q using the appropriate method for your environment:

import { Q } from '@joakimstai/q'

const { Q } = require('@joakimstai/q')

Create a queue

let queue = new Q()

You can also specify an array of items up front:

queue = new Q([1, 2, 3])

Add an item to the back/tail of the queue (enqueue)

queue.push(4)

Remove one item from the front/head of the queue (dequeue)

queue.shift() // 1

Returns undefined if the queue is empty.

Read any item in the queue by its index (peek)

queue.at(0)  // 2 (front)
queue.at(1)  // 3
queue.at(-1) // 4 (back)

Returns undefined for out-of-bounds indexes.

Get the size of the queue

queue.size() // 3

Check whether the queue has any items

Useful for iterating through the queue in a while loop.

while (queue.hasItems()) … // true

Reset the queue

queue.reset()

Optionally, specify an array of items to reset to:

queue.reset([1, 2, 3])

Get all the items in the queue as an array

queue.toArray() // [1, 2, 3]

That's it.

Performance

Below are the results of benchmarks adapted from denque, fast-fifo and data-structure-typed. They were executed on JavaScriptCore with bun using tinybench on a 2018 Mac Mini (3 GHz 6-Core Intel Core i5).

According to these benchmarks, Q is up there with the highly optimized denque and fast-fifo libraries, and much faster than using Array as a makeshift queue. Not bad for 252 bytes (minzipped)!

I admit to not knowing much about the dark arts of benchmarking, so I can't vouch for the accuracy of these results or offer an analysis. Take it for what it is. YMMV, grain of salt and all that.

$ bun run ./bench growth
[2.42s] [object Object] (size: 10,000, iterations: 1,000)
┌───┬──────────┬─────────┬───────────────────┬────────┬─────────┐
│   │ Library  │ ops/sec │ Average Time (ns) │ Margin │ Samples │
├───┼──────────┼─────────┼───────────────────┼────────┼─────────┤
│ 0 │ Denque   │ 2,503   │ 399,424           │ ±0.92% │ 1,252   │
│ 1 │ FastFIFO │ 2,406   │ 415,525           │ ±2.45% │ 1,204   │
│ 2 │ Q        │ 2,204   │ 453,532           │ ±1.75% │ 1,103   │
│ 3 │ Array    │ 769     │ 1,299,899         │ ±2.52% │ 385     │
└───┴──────────┴─────────┴───────────────────┴────────┴─────────┘

$ bun run ./bench push
[2.59s] [object Object] (size: 1,000, iterations: 1,000)
┌───┬──────────┬─────────┬───────────────────┬──────────┬─────────┐
│   │ Library  │ ops/sec │ Average Time (ns) │ Margin   │ Samples │
├───┼──────────┼─────────┼───────────────────┼──────────┼─────────┤
│ 0 │ Denque   │ 31,137  │ 32,115            │ ±116.17% │ 15,569  │
│ 1 │ FastFIFO │ 51,459  │ 19,432            │ ±54.75%  │ 26,608  │
│ 2 │ Q        │ 53,017  │ 18,861            │ ±88.73%  │ 26,509  │
│ 3 │ Array    │ 35,761  │ 27,963            │ ±105.16% │ 17,881  │
└───┴──────────┴─────────┴───────────────────┴──────────┴─────────┘

$ bun run ./bench push-shift
[2.44s] [object Object] (size: 1,000, iterations: 1,000)
┌───┬──────────┬─────────┬───────────────────┬────────┬─────────┐
│   │ Library  │ ops/sec │ Average Time (ns) │ Margin │ Samples │
├───┼──────────┼─────────┼───────────────────┼────────┼─────────┤
│ 0 │ Denque   │ 61,955  │ 16,140            │ ±0.35% │ 30,978  │
│ 1 │ FastFIFO │ 48,961  │ 20,424            │ ±0.40% │ 24,481  │
│ 2 │ Q        │ 41,098  │ 24,331            │ ±1.19% │ 20,550  │
│ 3 │ Array    │ 14,648  │ 68,266            │ ±2.15% │ 7,325   │
└───┴──────────┴─────────┴───────────────────┴────────┴─────────┘

$ bun run ./bench shift-push
[10.43s] [object Object] (size: 1,000, iterations: 1,000)
┌───┬──────────┬────────────┬───────────────────┬────────┬───────────┐
│   │ Library  │ ops/sec    │ Average Time (ns) │ Margin │ Samples   │
├───┼──────────┼────────────┼───────────────────┼────────┼───────────┤
│ 0 │ Denque   │ 11,487,654 │ 87                │ ±0.28% │ 5,743,828 │
│ 1 │ FastFIFO │ 10,000,355 │ 99                │ ±0.85% │ 5,000,178 │
│ 2 │ Q        │ 10,553,278 │ 94                │ ±0.72% │ 5,276,640 │
│ 3 │ Array    │ 5,928,301  │ 168               │ ±0.26% │ 2,964,151 │
└───┴──────────┴────────────┴───────────────────┴────────┴───────────┘