Deques are a generalization of stacks and queues (the name is pronounced "deck" and is short for "double-ended queue"). -- Python collections.

npm install @blakeembrey/deque --save

• size Returns the number of elements in the deque.
• push(x) Add x to right side of the deque.
• pushLeft(x) Add x to the left side of the deque.
• clear() Remove all elements from the deque leaving it with length 0.
• extend(iterable) Extend the right side of the deque by appending elements from iterable.
• extendLeft(iterable) Extend the left side of the deque by appending elements from iterable.
• peek(i) Return the element at index i in the deque.
• indexOf(x, start?) Return the position of x in the deque.
• has(x) Return a boolean indicating whether x is in the deque.
• insert(i, x) Insert x into the deque at position i.
• pop() Remove and return an element from the right side of the deque. If no elements are present, throws RangeError.
• popLeft() Return and return an element from the left side of the deque. If no elements are present, throws RangeError.
• delete(i) Delete the value at position i.
• reverse() Reverse the elements of the deque in-place.
• rotate(n=1) Rotate the deque n steps to the right.
• entries() Return an iterable of deque.
• @@iterator() Return an iterable of deque.

import { Deque } from '@blakeembrey/deque'

const d = new Deque('ghi')

for (const value of d) {
  console.log(value.toUpperCase()) //=> G H I
}

d.push('j')
d.pushLeft('f')
d //=> Deque(['f', 'g', 'h', 'i', 'j'])

d.pop() //=> 'j'
d.popLeft() //=> 'f'

Array.from(d) //=> ['g', 'h', 'i']

d.peek(0) //=> 'g'
d.peek(-1) //=> 'i'

d.extend('jkl')
d //=> Deque(['g', 'h', 'i', 'j', 'k', 'l'])

d.rotate(1)
d //=> Deque(['l', 'g', 'h', 'i', 'j', 'k'])

d.rotate(-1)
d //=> Deque(['g', 'h', 'i', 'j', 'k', 'l'])

const d2 = new Deque(d)

d2 //=> Deque(['g', 'h', 'i', 'j', 'k', 'l'])

This project uses TypeScript and publishes definitions on NPM.

Circular array implementation originally based on denque with additional optimizations.

Apache 2.0