Introduction article to the data structure. Queue concept and examples applied to the Javascript language.

Introduction

Data structures are a means of handling large amounts of data efficiently, Knowing its structure and composition gives us more effective tools to design our product in relation to certain problems. On this occasion we will perform a queue introduction, reviewing its peculiarity and use.

Queue concept

Queues are a dynamic data structure that allows elements to be stored and retrieved based on a structure FIFO(first in, first out). The given name comes from the analogy of a client queue in the bank. Customer who arrives first will be served first, and the one who arrives later will be placed at the end of the queue and so on.

Implement queue in Javascript

To implement a queue in Javascript we will rely on the repository https://github.com/trekhleb/javascript-algorithms that contains an excellent implementation, but we will simplify some methods and structures to be able to understand its operation. We will support everyone in object-oriented programming.

Queue class

Class to represent a queue, this class will have the property called itemsthat will represent a set of elements to store (in this case we will use an array of elements, but it can be of any other type, for example, objects or sets. The most important thing is to encapsulate the behavior). At startup, the itemsproperty will have no elements.

class Queue{
  constructor() {
    this.items = [];
  }
}

the next steps will be to add to class Queuemethods that will help us to make the manipulation of elements in our queue.

Method to insert elements

To insert items into our queue, we create the common method called enqueue.

enqueue()

enqueue(element) {
  this.items.push(element);
}

Element removal method

to remove elements in our queue, we will create the common method called dequeue. This method aims to dequeue elements in our queue.

dequeue()

dequeue() {
  return this.items.shift();
}

Element display method

Another more common queue operation is the display of the element that is about to exit. This method is commonly called peek.

peek()

peek() {
  return this.items[this.items.length - 1];
}

Full code

Ending

In this article we deal with queues in a simple way, however, these methods should be enough to cover the basic use cases. Of course, there are many ways to extend and refine our example. I recommend to continue exploring implementations and adapt them to your need.

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