Implementing Queue in JavaScript

In this blog, we’re going to discuss how to implement queues in JavaScript. Specifically, we’ll cover two approaches: one using an array and another using a linked list.

Implementing Queue using Array in JavaScript

Let’s kick things off with a simple implementation using an array. In JavaScript, arrays are versatile data structures, making them suitable for implementing queues. Here’s a basic example:

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

  // Add an element to the queue
  enqueue(element) {
    this.items.push(element);
  }

  // Remove and return the front element from the queue
  dequeue() {
    if (this.isEmpty()) {
      console.log("Queue is empty");
      return null; // or throw new Error("Queue is empty");
    }
    return this.items.shift();
  }

  // Return the front element without removing it
  front() {
    if (this.isEmpty()) {
      console.log("Queue is empty");
      return null; // or throw new Error("Queue is empty");
    }
    return this.items[0];
  }

  // Check if the queue is empty
  isEmpty() {
    return this.items.length === 0;
  }

  // Return the size of the queue
  size() {
    return this.items.length;
  }

  // Print the elements of the queue
  print() {
    console.log(this.items.join(" "));
  }
}

// Example usage:
const queue = new Queue();

queue.enqueue(10);
queue.enqueue(20);
queue.enqueue(30);

console.log("Front element:", queue.front()); // Front element: 10

console.log("Queue size:", queue.size()); // Queue size: 3

console.log("Dequeue:", queue.dequeue()); // Dequeue: 10

queue.print(); // 20 30

In this implementation, we have a Queue class with methods for enqueue, dequeue, checking if the queue is empty, getting the front element, and more.