michaeltheriot / js-queue

A linked-list implementation of a queue in JavaScript.

Queue

This is a linked-list implementation of a queue.

Multiple arguments can be taken in the constructor to add to the queue.

var q = new Queue();

q.enqueue(5); // 1 (length)
q.enqueue(6); // 2
q.enqueue(7); // 3

q.dequeue(); // 5
q.dequeue(); // 6
q.dequeue(); // 7

.enqueue(...item), .push(...item)

Add elements to the queue using enqueue or its alias push. These can take multiple arguments and will queue the items in FIFO order.

var q = new Queue();

q.enqueue(5, 6, 7); // 3

q.dequeue(); // 5
q.dequeue(); // 6
q.dequeue(); // 7

.dequeue(), .shift()

dequeue and its alias shift removes and returns the first element in the queue.

.unshift(...item)

Adds an item to the front of the queue.

var q = new Queue(5, 6, 7);

q.unshift(1); // 4

q.dequeue(); // 1
q.dequeue(); // 5
q.dequeue(); // 6
q.dequeue(); // 7

.pop()

Removes an item from the end of the queue.

This method is in O(n) time.

var q = new Queue(5, 6, 7);

q.pop(); // 7

.first

Returns the first item in the queue without removing it.

.last

Returns the last item in the queue without removing it.

.length

Returns the number of items in the queue.

Iteratable

Queues are an iterable and iterating them does not affect their contents.

var q = new Queue(1, 2, 3);

for(var item of q) {
  console.log(item); // 1, 2, 3
}

Queue.from([[iterable]])

Queues can be created from an iterable using Queue.from.

var set = new Set([1, 2, 3]);
var q = Queue.from(set);

while(q.length) {
  q.dequeue(); // 1, 2, 3
}