Queue

Queue provides a simple JavaScript-native implementation of the queue data structure.

Installation

Using npm:

$ npm install @bletchley-tech/queue

Usage

Queue provides a JavaScript-native implementation of the queue data structure designed for use in a synchronous Node.js environment.

The package provides a single class, Queue, which is a simple queue data structure. To use it, follow the next steps:

1. Import/Require the package:

   // CommonJS
   const Queue = require('queue');
   
   // ES6+
   import Queue from 'queue';

   This will load the Queue class into the global namespace and allow you to create new instances of Queue.

2. Create a new instance of Queue:

   const queue = new Queue();

   This will create a new instance of Queue and store it in the queue variable.

3. Use the queue:

   queue.enqueue(1); // Enqueue 1
   queue.size; // 1
   queue.isEmpty; // false
   queue.queue; // '1'

   This will enqueue 1. Enqueueing a value will add it to the end of the queue, and automatically update the size.

Queue Class

The Queue class has only one property, queue, which is an array of values. The specific functinoality of the Queue data structure is provided through class methods.

The Queue class takes advantage of the new private class properties/methods JavaScript feature introduced in ES2022. This means that once the Queue is initialized, it will not be able to be changed except by the class' own methods.

Version 2.0.0 Update

For version 2.0.0, the Queue data structure was defined to only accept one data type within itself to enforce data consistency. This was done to prevent the Queue from being used to store mixed data types.

Constructor

The Queue class has a constructor that takes either one or no arguments.

If no arguments are passed, the constructor returns a new, empty Queue instance.

If one argument is passed, the constructor acts as a copy constructor. This means the passed argument must be an instance of Queue, to be copied into a new instance which will be returned by the constructor.

const queue = new Queue(); // Create a new empty Queue
queue.enqueueMany(5, 1, 9); // Enqueue 5, 1, 9

const queue2 = new Queue(queue); // Create a new Queue (queue2) with the same values as queue

Class Methods

enqueue(value)

The enqueue method adds a value to the end of the queue.

queue.enqueue(1); // Enqueue 1

enqueueMany(values)

The enqueueMany method adds multiple values to the end of the queue.

queue.enqueueMany(1, 2, 3); // Enqueue 1, 2, 3

dequeue()

The dequeue method removes the value at the front of the queue.

queue.dequeue(); // Dequeue 1

Class Attributes

size

queue.size; // 2

This will return the size of the queue.

isEmpty

queue.isEmpty; // false

This will return true if the queue is empty, false otherwise.

front

queue.front; // 2

This will return the value at the front of the queue.

queue

queue.queue; // '2 - 3'

This will return the queue as a string.

type

queue.type; // 'number'

License

Queue is licensed under the MIT license (see the LICENSE file for more information).