SOURCE

function Queue(){
    this.dateStore = [];
    this.addqueue = addqueue;
    this.dequeue = dequeue;
    this.front = front;
    this.back = back;
    this.toString = toString;
    this.empty = empty;
}

function addqueue(element){
    this.dateStore.push(element);
}

function dequeue(){
    return this.dateStore.shift();
}

function front(){
    return this.dateStore[0];
}

function back(){
    return this.dateStore[this.dateStore.length -1];
}

function toString(){
    var retStr = '';
    for(var i = 0;i<this.dateStore.length;i++){
        retStr += this.dateStore[i] + '\n'
    }
    return retStr;
}

function empty(){
    if(this.dateStore.length == 0){
        return true;
    }
    else{
        return false;
    }
}

//test
var q = new Queue();
q.addqueue('aaa');
q.addqueue('bbb');
q.addqueue('ccc');
q.addqueue('ddd');
q.addqueue('fff');
console.log(q.toString());
q.dequeue();
console.log(q.toString());
console.log(q.front());
console.log(q.back());