JavaScript examples

queue.js

/* Implementing a JavaScript queue using an array
*  English      > https://www.javascripttutorial.net/javascript-queue/
*  Portugues    > https://medium.com/@ricardoreis_22930/queue-fila-9a7cf32c1132
*/
function Queue(){
    this.elements = []
}

// enqueue method adds an element at the end of the queue 
Queue.prototype.enqueue = function (e) {
    // insert the new element 
    this.elements.push(e);
}

// remove an element from the front of the queue
Queue.prototype.dequeue = function () {
    return this.elements.shift();
}
 
// check if the queue is empty
Queue.prototype.isEmpty = function () {
    return this.elements.length == 0;
}

// get the element at the front of the queue
Queue.prototype.peek = function () {
    return !this.isEmpty() ? this.elements[0] : undefined;
}

// to query the length of a queue
Queue.prototype.length = function () {
    return this.elements.length;
}

// to create a neq queue from the Queue() contructor function
let q = new Queue();

// to enqueue numbers from 1 to 7 
for (let i = 1; i <= 7; i++){
    q.enqueue(i);  
}

// to get the value of the q variable 
console.log(q);

// to get the number at the front of the queue 
console.log(`Number at the front of the queue: ${q.peek()}`);

//to get the current length of the queue
console.log(`The length of the queue: ${q.length()}`);

// to remove the element at the front of the queue (dequeue all elements)
while (!q.isEmpty()){
    console.log(q.dequeue());
}