// Copyright 2020 Rajdeep Chandra

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

let Queue = function () {

let collection = [];

// prints the queue

this.print = function(){

console.log(collection)

}

// pushes an item to the queue

this.enqueue = function(element){

collection.push(element);

}

// remove an item from the queue, in queue the first item is removed ie in FIFO

this.dequeue = function(){

collection.shift(); // shift method removes the first item of an array

}

// returning the size of the queue

this.size = function(){

return collection.length

}

//printing the first item of the queue

this.front = function(){

return collection[0];

}

// checking if the queue is empty or not

this.isEmpty = function(){

return (collection.length === 0)

}

}

// Running the program

let q = new Queue();

// Adding an element to the tail of the queue

q.enqueue("a");

q.enqueue("b");

q.enqueue("c");

q.print();

// Removing an element from the queue

q.dequeue();

console.log(q.front());

q.print();