08-circular-queue.js

class CircularQueue{
    constructor(size){
        this.size = size
        this.items = new Array(size).fill(null)
        this.front = this.rear = -1
    }
    enqueue(value){
        if( (this.rear + 1)% this.size  == this.front ){
            console.log("Queue is full")
        }else if(this.front === -1){
            this.rear = this.front = 0
            this.items[this.rear] = value
        }else{
            this.rear = (this.rear + 1) % this.size
            this.items[this.rear] = value
        }
    }

    dequeue(){
        if(this.front == -1){
            console.log("Queue is empty")
        }else if(this.front === this.rear){
            console.log(this.items[this.front])
            this.front = this.rear = -1
        }else{
            console.log(this.items[this.front])
            this.front =  (this.front +1) % this.size
        }
    }
}

let cq = new CircularQueue(5)
cq.enqueue(10)
cq.enqueue(20)
cq.enqueue(30)
cq.enqueue(40)
cq.enqueue(50)
cq.dequeue()
cq.enqueue(60)
cq.dequeue()
cq.dequeue()
cq.dequeue()
cq.dequeue()
cq.dequeue()
cq.dequeue()