# yocto-queue [![](https://badgen.net/bundlephobia/minzip/yocto-queue)](https://bundlephobia.com/result?p=yocto-queue)

> Tiny queue data structure

You should use this package instead of an array if you do a lot of `Array#push()` and `Array#shift()` on large arrays, since `Array#shift()` has [linear time complexity](https://medium.com/@ariel.salem1989/an-easy-to-use-guide-to-big-o-time-complexity-5dcf4be8a444#:~:text=O(N)%E2%80%94Linear%20Time) *O(n)* while `Queue#dequeue()` has [constant time complexity](https://medium.com/@ariel.salem1989/an-easy-to-use-guide-to-big-o-time-complexity-5dcf4be8a444#:~:text=O(1)%20%E2%80%94%20Constant%20Time) *O(1)*. That makes a huge difference for large arrays.

> A [queue](https://en.wikipedia.org/wiki/Queue_(abstract_data_type)) is an ordered list of elements where an element is inserted at the end of the queue and is removed from the front of the queue. A queue works based on the first-in, first-out ([FIFO](https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics))) principle.

## Install

```sh
npm install yocto-queue
```

## Usage

```js
import Queue from 'yocto-queue';

const queue = new Queue();

queue.enqueue('🦄');
queue.enqueue('🌈');

console.log(queue.size);
//=> 2

console.log(...queue);
//=> '🦄 🌈'

console.log(queue.dequeue());
//=> '🦄'

console.log(queue.dequeue());
//=> '🌈'
```

## API

### `queue = new Queue()`

The instance is an [`Iterable`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols), which means you can iterate over the queue front to back with a “for…of” loop, or use spreading to convert the queue to an array. Don't do this unless you really need to though, since it's slow.

#### `.enqueue(value)`

Add a value to the queue.

#### `.dequeue()`

Remove the next value in the queue.

Returns the removed value or `undefined` if the queue is empty.

#### `.peek()`

Get the next value in the queue without removing it.

Returns the value or `undefined` if the queue is empty.

#### `.clear()`

Clear the queue.

#### `.size`

The size of the queue.

## Related

- [quick-lru](https://github.com/sindresorhus/quick-lru) - Simple “Least Recently Used” (LRU) cache