How to implement a queue in JavaScript

A queue is a data structure that follows FIFO (First In First Out). Think of the queue as a list in which the element that is inserted first will also be accessed first.

Think of it as a ticket counter, where the first person in line will get the first ticket.

// program to implement a queue data structure
class Queue {
    constructor() {
        this.queue = [];
    }
   
    enqueue(element) { // add element
        return this.queue.push(element);
    }
    
    dequeue() { 
        if(this.queue.length > 0) {
            return this.queue.shift();   // remove first element
        }
    }
    
    peek() {
        return this.queue[this.queue.length - 1];
    }
      
    size(){
        return this.queue.length;
    }
    isEmpty() {
       return this.queue.length == 0;
    }
    clear(){
        this.queue = [];
    }
}
let counter =  new Queue();
// add
counter.enqueue(1);
counter.enqueue(2);
counter.enqueue(3);
// get last element 
console.log(counter.peek()); // 3
// remove
console.log(counter.dequeue()); // 1
console.log(counter.dequeue()); // 2
console.log(counter.isEmpty()); // false
console.log(counter.size()); // 1
counter.clear(); 
console.log(counter.size()); // 0

How to implement a queue in JavaScript

Complexity of queue operations