README
@datastructures-js/queue
A performant queue implementation in javascript.
Contents
Install
npm install --save @datastructures-js/queue
require
const { Queue } = require('@datastructures-js/queue');
import
import { Queue } from '@datastructures-js/queue';
API
constructor
JS
// empty queue
const queue = new Queue();
// from an array
const queue = new Queue([1, 2, 3]);
TS
// empty queue
const queue = new Queue<number>();
// from an array
const queue = new Queue<number>([1, 2, 3]);
Queue.fromArray(elements)
JS
// empty queue
const queue = Queue.fromArray([]);
// with elements
const list = [10, 3, 8, 40, 1];
const queue = Queue.fromArray(list);
// If the list should not be mutated, use a copy of it.
const queue = Queue.fromArray(list.slice());
TS
// empty queue
const queue = Queue.fromArray<number>([]);
// with elements
const list = [10, 3, 8, 40, 1];
const queue = Queue.fromArray<number>(list);
.enqueue(element)
adds an element at the back of the queue.
| params | return | runtime |
|---|---|---|
| element: T | Queue<T> | O(1) |
queue.enqueue(10).enqueue(20);
.front()
peeks on the front element of the queue.
| return | runtime |
|---|---|
| T | O(1) |
console.log(queue.front()); // 10
.back()
peeks on the back element in the queue.
| return | runtime |
|---|---|
| T | O(1) |
console.log(queue.back()); // 20
.dequeue()
dequeue the front element in the queue. It does not use .shift() to dequeue the element. Instead, it uses a pointer to get the front element and only remove elements when reaching half size of the queue.
| return | runtime |
|---|---|
| T | O(n*log(n)) |
console.log(queue.dequeue()); // 10
console.log(queue.front()); // 20
Dequeuing all elements takes O(n*log(n)) instead of O(n2) when using shift().
benchmark:
dequeuing 1 million elements in Node v12
| .dequeue() | .shift() |
| ~ 40 ms | ~ 3 minutes |
.isEmpty()
checks if the queue is empty.
| return | runtime |
|---|---|
| boolean | O(1) |
console.log(queue.isEmpty()); // false
.size()
returns the number of elements in the queue.
| return | runtime |
|---|---|
| number | O(1) |
console.log(queue.size()); // 1
.clone()
creates a shallow copy of the queue.
| return | runtime |
|---|---|
| Queue<T> | O(n) |
const queue = Queue.fromArray([{ id: 2 }, { id: 4 } , { id: 8 }]);
const clone = queue.clone();
clone.dequeue();
console.log(queue.front()); // { id: 2 }
console.log(clone.front()); // { id: 4 }
.toArray()
returns a copy of the remaining elements as an array.
| return | runtime |
|---|---|
| T[] | O(n) |
queue.enqueue(4).enqueue(2);
console.log(queue.toArray()); // [20, 4, 2]
.clear()
clears all elements from the queue.
| runtime |
|---|
| O(1) |
queue.clear();
queue.size(); // 0
Build
grunt build
License
The MIT License. Full License is here