Queue

Queue data structure implementation in javascript.

While you can mimic queue(FIFO) behavior via arrays like so:

  const arr = [];
  // "queue" some data up
  arr.push(1);
  arr.push(2);
  arr.push(3);

  console.log(arr.shift()) // 1

This operation causes the array indices to be recalculated resulting in O(n) time for each dequeue made (push is 0(1) time operation).

Alternative

To avoid O(n) dequeue times we can instead use a hash table and keep track of of head and tail indexes of the table. This allows enqueue and dequeue to operate in O(1) time!

Check out index.js to see a very simple implementation of this behavior.

Install

  npm install jsQueue

Usage

  const q = new Queue();

  // NOTE: enqueue returns the queue object so we can chain enqueue methods
  q.enqueue('some').enqueue('test').enqueue('data');

  console.log(q.dequeue()) // 'some'
  console.log(q.dequeue()) // 'test'
  console.log(q.dequeue()) // 'data'
  console.log(q.dequeue()) // false

  console.log(q.size) // 0

  q.enqueue('something');

  // peek lets us check whats next without dequeuing it
  console.log(q.peek()) // 'something'

  q.enqueue('some').enqueue('more').enqueue.('data');

  console.log(q.size) // 4