@datastructures-js/queue

A highly performant queue implementation in javascript.

Table of Contents

• Install
• API
  • require
  • import
  • Creating a Queue
    • Empty Queue
    • From an Existing Array
  • .enqueue(element)
  • .front()
  • .back()
  • .dequeue()
  • .isEmpty()
  • .size()
  • .toArray()
  • .clear()
• Build

Install

npm install --save @datastructures-js/queue

API

require

const Queue = require('@datastructures-js/queue');

import

import Queue from '@datastructures-js/queue';

Create a Queue

empty queue

const queue = new Queue();

// OR

const queue = Queue.fromArray([]);

from an existing array

const list = [10, 3, 8, 40, 1];

const queue = new Queue(list);

// OR

const queue = Queue.fromArray(list);

If the list should not be mutated, simply construct the queue from a copy of it.

const queue = new Queue(list.slice(0));

.enqueue(element)

adds an element at the back of the queue.

queue.enqueue(10);
queue.enqueue(20);

.front()

peeks on the front element of the queue.

console.log(queue.front()); // 10

.back()

peeks on the back element in the queue.

console.log(queue.back()); // 20

.dequeue()

dequeue the front element in the queue. It does not use .shift() to dequeue an element. Instead, it uses an offset to get the front element and only remove elements when reaching half size of the queue.

console.log(queue.dequeue()); // 10
console.log(queue.front()); // 20

Dequeuing all elements takes O(n*log(n)) instead of O(n²) if using shift().

Here's a benchmark:

.isEmpty()

checks if the queue is empty.

console.log(queue.isEmpty()); // false

.size()

returns the number of elements in the queue.

console.log(queue.size()); // 1

.clone()

creates a shallow copy of the queue.

const queue = Queue.fromArray([{ id: 2 }, { id: 4 } , { id: 8 }]);
const clone =  queue.clone();

clone.dequeue();

console.log(queue.front()); // { id: 2 }
console.log(clone.front()); // { id: 4 }

.toArray()

returns a copy of the remaining elements as an array.

queue.enqueue(4);
queue.enqueue(2);
console.log(queue.toArray()); // [20, 4, 2]

.clear()

clears all elements from the queue.

queue.clear();
queue.size(); // 0

Build

lint + tests

grunt build

License

The MIT License. Full License is here