--description--

Like stacks, queues are a collection of elements. But unlike stacks, queues follow the FIFO (First-In First-Out) principle. Elements added to a queue are pushed to the tail, or the end, of the queue, and only the element at the front of the queue is allowed to be removed.

We could use an array to represent a queue, but just like stacks, we want to limit the amount of control we have over our queues.

The two main methods of a queue class is the enqueue and the dequeue method. The enqueue method pushes an element to the tail of the queue, and the dequeue method removes and returns the element at the front of the queue. Other useful methods are the front, size, and isEmpty methods.

--instructions--

Write an enqueue method that pushes an element to the tail of the queue, a dequeue method that removes and returns the front element, a front method that lets us see the front element, a size method that shows the length, and an isEmpty method to check if the queue is empty.

--hints--

Your Queue class should have a enqueue method.

assert(
  (function () {
    var test = new Queue();
    return typeof test.enqueue === 'function';
  })()
);

Your Queue class should have a dequeue method.

assert(
  (function () {
    var test = new Queue();
    return typeof test.dequeue === 'function';
  })()
);

Your Queue class should have a front method.

assert(
  (function () {
    var test = new Queue();
    return typeof test.front === 'function';
  })()
);

Your Queue class should have a size method.

assert(
  (function () {
    var test = new Queue();
    return typeof test.size === 'function';
  })()
);

Your Queue class should have an isEmpty method.

assert(
  (function () {
    var test = new Queue();
    return typeof test.isEmpty === 'function';
  })()
);

The dequeue method should remove and return the front element of the queue

assert(
  (function () {
    var test = new Queue();
    test.enqueue('Smith');
    test.enqueue('John');
    return test.dequeue() === 'Smith';
  })()
);

The front method should return value of the front element of the queue

assert(
  (function () {
    var test = new Queue();
    test.enqueue('Smith');
    test.enqueue('John');
    return test.front() === 'Smith';
  })()
);

The size method should return the length of the queue

assert(
  (function () {
    var test = new Queue();
    test.enqueue('Smith');
    return test.size() === 1;
  })()
);

The isEmpty method should return false if there are elements in the queue

assert(
  (function () {
    var test = new Queue();
    test.enqueue('Smith');
    return !test.isEmpty();
  })()
);

--seed--

--seed-contents--

function Queue() {
  var collection = [];
  this.print = function() {
    console.log(collection);
  };
  // Only change code below this line

  // Only change code above this line
}

--solutions--

function Queue () { 
    var collection = [];
    this.print = function() {
        console.log(collection);
    };
    // Only change code below this line
    this.enqueue = function(item) {
        collection.push(item);
    }

    this.dequeue = function() {
        return collection.shift();
    }

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

    this.size = function(){
        return collection.length;
    }

    this.isEmpty = function() {
        return collection.length === 0 ? true : false;
    }
    // Only change code above this line
}